Localise dependency on boost::format and improve logging API

30 files changed, 185 insertions, 207 deletions

diff --git a/src/AtomReader.cpp b/src/AtomReader.cpp
index cc47498f..71d88a84 100644
--- a/src/AtomReader.cpp
+++ b/src/AtomReader.cpp
@@ -45,7 +45,7 @@ AtomReader::get_atom(const LV2_Atom* in, Atom& out)
 			if (uri) {
 				out = Atom(sizeof(int32_t), _uris.atom_URID, &urid->body);
 			} else {
-				_log.error(fmt("Unable to unmap URID %1%\n") % urid->body);
+				_log.error("Unable to unmap URID %1%\n", urid->body);
 			}
 		} else {
 			out = Atom(in->size, in->type, LV2_ATOM_BODY_CONST(in));
@@ -78,7 +78,7 @@ AtomReader::atom_to_uri(const LV2_Atom* atom)
 		if (URI::is_valid(str)) {
 			return URI(str);
 		} else {
-			_log.warn(fmt("Invalid URI <%1%>\n") % str);
+			_log.warn("Invalid URI <%1%>\n", str);
 		}
 	} else if (atom->type == _uris.atom_Path) {
 		const char* str = (const char*)LV2_ATOM_BODY_CONST(atom);
@@ -92,7 +92,7 @@ AtomReader::atom_to_uri(const LV2_Atom* atom)
 		if (str) {
 			return URI(str);
 		} else {
-			_log.warn(fmt("Unknown URID %1%\n") % str);
+			_log.warn("Unknown URID %1%\n", str);
 		}
 	}
 	return boost::optional<URI>();
@@ -144,8 +144,7 @@ bool
 AtomReader::write(const LV2_Atom* msg, int32_t default_id)
 {
 	if (msg->type != _uris.atom_Object) {
-		_log.warn(fmt("Unknown message type <%1%>\n")
-		          % _map.unmap_uri(msg->type));
+		_log.warn("Unknown message type <%1%>\n", _map.unmap_uri(msg->type));
 		return false;
 	}
 
@@ -374,8 +373,8 @@ AtomReader::write(const LV2_Atom* msg, int32_t default_id)
 	} else if (obj->body.otype == _uris.ingen_BundleEnd) {
 		_iface(BundleEnd{seq});
 	} else {
-		_log.warn(fmt("Unknown object type <%1%>\n")
-		          % _map.unmap_uri(obj->body.otype));
+		_log.warn("Unknown object type <%1%>\n",
+		          _map.unmap_uri(obj->body.otype));
 	}
 
 	return true;
diff --git a/src/Configuration.cpp b/src/Configuration.cpp
index d0d606e8..003480ea 100644
--- a/src/Configuration.cpp
+++ b/src/Configuration.cpp
@@ -141,9 +141,8 @@ Configuration::set_value_from_string(Configuration::Option& option,
 		if (endptr && *endptr == '\0') {
 			option.value = _forge.make(intval);
 		} else {
-			throw OptionError(
-				(fmt("Option `%1%' has non-integer value `%2%'")
-				 % option.name % value).str());
+			throw OptionError(fmt("Option `%1%' has non-integer value `%2%'",
+			                      option.name, value));
 		}
 	} else if (option.type == _forge.String) {
 		option.value = _forge.alloc(value.c_str());
@@ -152,8 +151,7 @@ Configuration::set_value_from_string(Configuration::Option& option,
 		option.value = _forge.make(bool(!strcmp(value.c_str(), "true")));
 		assert(option.value.type() == _forge.Bool);
 	} else {
-		throw OptionError(
-			(fmt("Bad option type `%1%'") % option.name).str());
+		throw OptionError(fmt("Bad option type `%1%'", option.name));
 	}
 	return EXIT_SUCCESS;
 }
@@ -181,17 +179,15 @@ Configuration::parse(int argc, char** argv)
 
 			const Options::iterator o = _options.find(name);
 			if (o == _options.end()) {
-				throw OptionError(
-					(fmt("Unrecognized option `%1%'") % name).str());
-			} else if (o->second.type == _forge.Bool) {  // --flag
+				throw OptionError(fmt("Unrecognized option `%1%'", name));
+			} else if (o->second.type == _forge.Bool) { // --flag
 				o->second.value = _forge.make(true);
 			} else if (equals) {  // --opt=val
 				set_value_from_string(o->second, equals + 1);
 			} else if (++i < argc) {  // --opt val
 				set_value_from_string(o->second, argv[i]);
 			} else {
-				throw OptionError(
-					(fmt("Missing value for `%1%'") % name).str());
+				throw OptionError(fmt("Missing value for `%1%'", name));
 			}
 		} else {
 			// Short option
@@ -200,15 +196,14 @@ Configuration::parse(int argc, char** argv)
 				const char                 letter = argv[i][j];
 				const ShortNames::iterator n      = _short_names.find(letter);
 				if (n == _short_names.end()) {
-					throw OptionError(
-						(fmt("Unrecognized option `%1%'") % letter).str());
+					throw OptionError(fmt("Unrecognized option `%1%'", letter));
 				}
 
 				const Options::iterator o = _options.find(n->second);
 				if (j < len - 1) {  // Non-final POSIX style flag
 					if (o->second.type != _forge.Bool) {
 						throw OptionError(
-							(fmt("Missing value for `%1%'") % letter).str());
+							fmt("Missing value for `%1%'", letter));
 					}
 					o->second.value = _forge.make(true);
 				} else if (o->second.type == _forge.Bool) {  // -f
@@ -216,8 +211,7 @@ Configuration::parse(int argc, char** argv)
 				} else if (++i < argc) {  // -v val
 					set_value_from_string(o->second, argv[i]);
 				} else {
-					throw OptionError(
-						(fmt("Missing value for `%1%'") % letter).str());
+					throw OptionError(fmt("Missing value for `%1%'", letter));
 				}
 			}
 		}
@@ -275,16 +269,16 @@ Configuration::save(URIMap&            uri_map,
 	// Create parent directories if necessary
 	const FilePath dir = path.parent_path();
 	if (!filesystem::create_directories(dir)) {
-		throw FileError((fmt("Error creating directory %1% (%2%)")
-		                 % dir % strerror(errno)).str());
+		throw FileError(fmt("Error creating directory %1% (%2%)",
+		                    dir, strerror(errno)));
 	}
 
 	// Attempt to open file for writing
 	std::unique_ptr<FILE, decltype(&fclose)> file{fopen(path.c_str(), "w"),
 	                                              &fclose};
 	if (!file) {
-		throw FileError((fmt("Failed to open file %1% (%2%)")
-		                 % path % strerror(errno)).str());
+		throw FileError(fmt("Failed to open file %1% (%2%)",
+		                    path, strerror(errno)));
 	}
 
 	// Use the file's URI as the base URI
diff --git a/src/Parser.cpp b/src/Parser.cpp
index c4439ed3..caebc5f1 100644
--- a/src/Parser.cpp
+++ b/src/Parser.cpp
@@ -165,7 +165,7 @@ get_port(ingen::World&     world,
 		if (i == props.end()
 		    || i->second.type() != world.forge().Int
 		    || i->second.get<int32_t>() < 0) {
-			world.log().error(fmt("Port %1% has no valid index\n") % subject);
+			world.log().error("Port %1% has no valid index\n", subject);
 			return boost::optional<PortRecord>();
 		}
 		*index = i->second.get<int32_t>();
@@ -186,8 +186,7 @@ get_port(ingen::World&     world,
 	}
 
 	if (!Raul::Symbol::is_valid(sym)) {
-		world.log().error(fmt("Port %1% has invalid symbol `%2%'\n")
-		                  % subject % sym);
+		world.log().error("Port %1% has invalid symbol `%2%'\n", subject, sym);
 		return boost::optional<PortRecord>();
 	}
 
@@ -267,9 +266,8 @@ parse_block(ingen::World&               world,
 	}
 
 	if (!prototype.is_valid()) {
-		world.log().error(
-			fmt("Block %1% (%2%) missing mandatory lv2:prototype\n") %
-			subject % path);
+		world.log().error("Block %1% (%2%) missing mandatory lv2:prototype\n",
+		                  subject, path);
 		return boost::optional<Raul::Path>();
 	}
 
@@ -363,7 +361,7 @@ parse_graph(ingen::World&                 world,
 		boost::optional<PortRecord> port_record = get_port(
 			world, model, port, ctx, graph_path, &index);
 		if (!port_record) {
-			world.log().error(fmt("Invalid port %1%\n") % port);
+			world.log().error("Invalid port %1%\n", port);
 			return boost::optional<Raul::Path>();
 		}
 
@@ -371,8 +369,8 @@ parse_graph(ingen::World&                 world,
 		if (ports.find(index) == ports.end()) {
 			ports[index] = *port_record;
 		} else {
-			world.log().error(fmt("Ignored port %1% with duplicate index %2%\n")
-			                   % port % index);
+			world.log().error("Ignored port %1% with duplicate index %2%\n",
+			                  port, index);
 		}
 	}
 
@@ -414,7 +412,7 @@ parse_graph(ingen::World&                 world,
 			boost::optional<PortRecord> port_record = get_port(
 				world, model, port, subctx, block_path, nullptr);
 			if (!port_record) {
-				world.log().error(fmt("Invalid port %1%\n") % port);
+				world.log().error("Invalid port %1%\n", port);
 				return boost::optional<Raul::Path>();
 			}
 
@@ -606,7 +604,7 @@ Parser::parse_file(ingen::World&                 world,
 		*world.rdf_world(), manifest_uri, URI(INGEN__Graph));
 
 	if (resources.empty()) {
-		world.log().error(fmt("No graphs found in %1%\n") % path);
+		world.log().error("No graphs found in %1%\n", path);
 		return false;
 	}
 
@@ -644,12 +642,12 @@ Parser::parse_file(ingen::World&                 world,
 	model.load_file(env, SERD_TURTLE, file_uri);
 	serd_env_free(env);
 
-	world.log().info(fmt("Loading %1% from %2%\n") % uri % file_path);
+	world.log().info("Loading %1% from %2%\n", uri, file_path);
 	if (parent) {
-		world.log().info(fmt("Parent: %1%\n") % parent->c_str());
+		world.log().info("Parent: %1%\n", parent->c_str());
 	}
 	if (symbol) {
-		world.log().info(fmt("Symbol: %1%\n") % symbol->c_str());
+		world.log().info("Symbol: %1%\n", symbol->c_str());
 	}
 
 	Sord::Node subject(*world.rdf_world(), Sord::Node::URI, uri.string());
@@ -691,7 +689,7 @@ Parser::parse_string(ingen::World&                     world,
 	URI actual_base((const char*)serd_env_get_base_uri(env, nullptr)->buf);
 	serd_env_free(env);
 
-	world.log().info(fmt("Parsing string (base %1%)\n") % base_uri);
+	world.log().info("Parsing string (base %1%)\n", base_uri);
 
 	Sord::Node subject;
 	parse(world, target, model, actual_base, subject, parent, symbol, data);
diff --git a/src/Serialiser.cpp b/src/Serialiser.cpp
index 6a0991be..fb78162f 100644
--- a/src/Serialiser.cpp
+++ b/src/Serialiser.cpp
@@ -184,7 +184,7 @@ Serialiser::Impl::write_bundle(SPtr<const Node> graph, const URI& uri)
 		path = path.parent_path();
 	}
 
-	_world.log().info(fmt("Writing bundle %1%\n") % path);
+	_world.log().info("Writing bundle %1%\n", path);
 	filesystem::create_directories(path);
 
 	const FilePath   main_file     = path / "main.ttl";
@@ -250,8 +250,8 @@ Serialiser::Impl::finish()
 	if (_mode == Mode::TO_FILE) {
 		SerdStatus st = _model->write_to_file(_base_uri, SERD_TURTLE);
 		if (st) {
-			_world.log().error(fmt("Error writing file %1% (%2%)\n")
-			                   % _base_uri % serd_strerror(st));
+			_world.log().error("Error writing file %1% (%2%)\n",
+			                   _base_uri, serd_strerror(st));
 		}
 	} else {
 		ret = _model->write_to_string(_base_uri, SERD_TURTLE);
diff --git a/src/SocketReader.cpp b/src/SocketReader.cpp
index 590b40cd..0cbb63af 100644
--- a/src/SocketReader.cpp
+++ b/src/SocketReader.cpp
@@ -97,8 +97,8 @@ SocketReader::run()
 	std::unique_ptr<FILE, decltype(&fclose)> f{fdopen(_socket->fd(), "r"),
 	                                           &fclose};
 	if (!f) {
-		_world.log().error(fmt("Failed to open connection (%1%)\n")
-		                   % strerror(errno));
+		_world.log().error("Failed to open connection (%1%)\n",
+		                   strerror(errno));
 		// Connection gone, exit
 		_socket.reset();
 		return;
@@ -168,8 +168,7 @@ SocketReader::run()
 		if (st == SERD_FAILURE || !_msg_node) {
 			continue;  // Read nothing, e.g. just whitespace
 		} else if (st) {
-			_world.log().error(fmt("Read error: %1%\n")
-			                   % serd_strerror(st));
+			_world.log().error("Read error: %1%\n", serd_strerror(st));
 			continue;
 		}
 
diff --git a/src/URIMap.cpp b/src/URIMap.cpp
index 7c5774f8..46ca0108 100644
--- a/src/URIMap.cpp
+++ b/src/URIMap.cpp
@@ -64,7 +64,7 @@ LV2_URID
 URIMap::URIDMapFeature::map(const char* uri)
 {
 	if (!URI::is_valid(uri)) {
-		log.error(fmt("Attempt to map invalid URI <%1%>\n") % uri);
+		log.error("Attempt to map invalid URI <%1%>\n", uri);
 		return 0;
 	}
 	return urid_map.map(urid_map.handle, uri);
diff --git a/src/World.cpp b/src/World.cpp
index 233a7d36..338d6864 100644
--- a/src/World.cpp
+++ b/src/World.cpp
@@ -86,12 +86,12 @@ ingen_load_library(Log& log, const string& name)
 	if (*library) {
 		return library;
 	} else if (!module_path) {
-		log.error(fmt("Unable to find %1% (%2%)\n")
-		          % name % Library::get_last_error());
+		log.error("Unable to find %1% (%2%)\n",
+		          name, Library::get_last_error());
 		return nullptr;
 	} else {
-		log.error(fmt("Unable to load %1% from %2% (%3%)\n")
-		          % name % module_path % Library::get_last_error());
+		log.error("Unable to load %1% from %2% (%3%)\n",
+		          name, module_path, Library::get_last_error());
 		return nullptr;
 	}
 }
@@ -229,7 +229,7 @@ World::load_configuration(int& argc, char**& argv)
 	// Parse default configuration files
 	const auto files = _impl->conf.load_default("ingen", "options.ttl");
 	for (const auto& f : files) {
-		_impl->log.info(fmt("Loaded configuration %1%\n") % f);
+		_impl->log.info("Loaded configuration %1%\n", f);
 	}
 
 	// Parse command line options, overriding configuration file values
@@ -270,7 +270,7 @@ World::load_module(const char* name)
 	if (i != _impl->modules.end()) {
 		return true;
 	}
-	log().info(fmt("Loading %1% module\n") % name);
+	log().info("Loading %1% module\n", name);
 	std::unique_ptr<ingen::Library> lib = ingen_load_library(log(), name);
 	ingen::Module* (*module_load)() =
 		lib ? (ingen::Module* (*)())lib->get_function("ingen_module_load")
@@ -285,7 +285,8 @@ World::load_module(const char* name)
 		}
 	}
 
-	log().error(fmt("Failed to load module `%1%' (%2%)\n") % name % lib->get_last_error());
+	log().error("Failed to load module `%1%' (%2%)\n",
+	            name, lib->get_last_error());
 	return false;
 }
 
@@ -294,7 +295,7 @@ World::run_module(const char* name)
 {
 	auto i = _impl->modules.find(name);
 	if (i == _impl->modules.end()) {
-		log().error(fmt("Attempt to run unloaded module `%1%'\n") % name);
+		log().error("Attempt to run unloaded module `%1%'\n", name);
 		return false;
 	}
 
@@ -310,7 +311,7 @@ World::new_interface(const URI& engine_uri, SPtr<Interface> respondee)
 	const Impl::InterfaceFactories::const_iterator i =
 	        _impl->interface_factories.find(std::string(engine_uri.scheme()));
 	if (i == _impl->interface_factories.end()) {
-		log().warn(fmt("Unknown URI scheme `%1%'\n") % engine_uri.scheme());
+		log().warn("Unknown URI scheme `%1%'\n", engine_uri.scheme());
 		return SPtr<Interface>();
 	}
 
@@ -323,7 +324,7 @@ World::run(const std::string& mime_type, const std::string& filename)
 {
 	const Impl::ScriptRunners::const_iterator i = _impl->script_runners.find(mime_type);
 	if (i == _impl->script_runners.end()) {
-		log().warn(fmt("Unknown script MIME type `%1%'\n") % mime_type);
+		log().warn("Unknown script MIME type `%1%'\n", mime_type);
 		return false;
 	}
 
diff --git a/src/client/ClientStore.cpp b/src/client/ClientStore.cpp
index ad3b3c0d..1f71bf61 100644
--- a/src/client/ClientStore.cpp
+++ b/src/client/ClientStore.cpp
@@ -70,7 +70,7 @@ ClientStore::add_object(SPtr<ObjectModel> object)
 				(*this)[object->path()] = object;
 				_signal_new_object.emit(object);
 			} else {
-				_log.error(fmt("Object %1% with no parent\n") % object->path());
+				_log.error("Object %1% with no parent\n", object->path());
 			}
 		} else {
 			(*this)[object->path()] = object;
@@ -252,14 +252,14 @@ ClientStore::operator()(const Put& msg)
 			const Iterator    l = properties.find(_uris.rdfs_label);
 			SPtr<PluginModel> plug;
 			if (p == properties.end()) {
-				_log.error(fmt("Preset <%1%> with no plugin\n") % uri.c_str());
+				_log.error("Preset <%1%> with no plugin\n", uri.c_str());
 			} else if (l == properties.end()) {
-				_log.error(fmt("Preset <%1%> with no label\n") % uri.c_str());
+				_log.error("Preset <%1%> with no label\n", uri.c_str());
 			} else if (l->second.type() != _uris.forge.String) {
-				_log.error(fmt("Preset <%1%> label is not a string\n") % uri.c_str());
+				_log.error("Preset <%1%> label is not a string\n", uri.c_str());
 			} else if (!(plug = _plugin(p->second))) {
-				_log.error(fmt("Preset <%1%> for unknown plugin %2%\n")
-				           % uri.c_str() % _uris.forge.str(p->second, true));
+				_log.error("Preset <%1%> for unknown plugin %2%\n",
+				           uri.c_str(), _uris.forge.str(p->second, true));
 			} else {
 				plug->add_preset(uri, l->second.ptr<char>());
 			}
@@ -274,8 +274,7 @@ ClientStore::operator()(const Put& msg)
 	}
 
 	if (!uri_is_path(uri)) {
-		_log.error(fmt("Put for unknown subject <%1%>\n")
-		           % uri.c_str());
+		_log.error("Put for unknown subject <%1%>\n", uri.c_str());
 		return;
 	}
 
@@ -315,7 +314,7 @@ ClientStore::operator()(const Put& msg)
 			bm->set_properties(properties);
 			add_object(bm);
 		} else {
-			_log.warn(fmt("Block %1% has no prototype\n") % path.c_str());
+			_log.warn("Block %1% has no prototype\n", path.c_str());
 		}
 	} else if (is_port) {
 		PortModel::Direction pdir = (is_output)
@@ -331,7 +330,7 @@ ClientStore::operator()(const Put& msg)
 		p->set_properties(properties);
 		add_object(p);
 	} else {
-		_log.warn(fmt("Ignoring %1% of unknown type\n") % path.c_str());
+		_log.warn("Ignoring %1% of unknown type\n", path.c_str());
 	}
 }
 
@@ -345,8 +344,7 @@ ClientStore::operator()(const Delta& msg)
 	}
 
 	if (!uri_is_path(uri)) {
-		_log.error(fmt("Delta for unknown subject <%1%>\n")
-		           % uri.c_str());
+		_log.error("Delta for unknown subject <%1%>\n", uri.c_str());
 		return;
 	}
 
@@ -357,7 +355,7 @@ ClientStore::operator()(const Delta& msg)
 		obj->remove_properties(msg.remove);
 		obj->add_properties(msg.add);
 	} else {
-		_log.warn(fmt("Failed to find object `%1%'\n") % path.c_str());
+		_log.warn("Failed to find object `%1%'\n", path.c_str());
 	}
 }
 
@@ -369,8 +367,8 @@ ClientStore::operator()(const SetProperty& msg)
 	const auto& value       = msg.value;
 
 	if (subject_uri == URI("ingen:/engine")) {
-		_log.info(fmt("Engine property <%1%> = %2%\n")
-		          % predicate.c_str() % _uris.forge.str(value, false));
+		_log.info("Engine property <%1%> = %2%\n",
+		          predicate.c_str(), _uris.forge.str(value, false));
 		return;
 	}
 	SPtr<Resource> subject = _resource(subject_uri);
@@ -387,8 +385,8 @@ ClientStore::operator()(const SetProperty& msg)
 		if (plugin) {
 			plugin->set_property(predicate, value);
 		} else if (predicate != _uris.ingen_activity) {
-			_log.warn(fmt("Property <%1%> for unknown object %2%\n")
-			          % predicate.c_str() % subject_uri.c_str());
+			_log.warn("Property <%1%> for unknown object %2%\n",
+			          predicate.c_str(), subject_uri.c_str());
 		}
 	}
 }
@@ -416,8 +414,8 @@ ClientStore::connection_graph(const Raul::Path& tail_path,
 	}
 
 	if (!graph) {
-		_log.error(fmt("Unable to find graph for arc %1% => %2%\n")
-		           % tail_path % head_path);
+		_log.error("Unable to find graph for arc %1% => %2%\n",
+		           tail_path, head_path);
 	}
 
 	return graph;
@@ -436,8 +434,7 @@ ClientStore::attempt_connection(const Raul::Path& tail_path,
 		graph->add_arc(arc);
 		return true;
 	} else {
-		_log.warn(fmt("Failed to connect %1% => %2%\n")
-		          % tail_path % head_path);
+		_log.warn("Failed to connect %1% => %2%\n", tail_path, head_path);
 		return false;
 	}
 }
@@ -466,8 +463,8 @@ ClientStore::operator()(const DisconnectAll& msg)
 	SPtr<ObjectModel> object = _object(msg.path);
 
 	if (!graph || !object) {
-		_log.error(fmt("Bad disconnect all notification %1% in %2%\n")
-		           % msg.path % msg.graph);
+		_log.error("Bad disconnect all notification %1% in %2%\n",
+		           msg.path, msg.graph);
 		return;
 	}
 
diff --git a/src/client/PluginUI.cpp b/src/client/PluginUI.cpp
index 5f954b85..c093ad47 100644
--- a/src/client/PluginUI.cpp
+++ b/src/client/PluginUI.cpp
@@ -32,9 +32,9 @@ static SPtr<const PortModel>
 get_port(PluginUI* ui, uint32_t port_index)
 {
 	if (port_index >= ui->block()->ports().size()) {
-		ui->world().log().error(
-			fmt("%1% UI tried to access invalid port %2%\n")
-			% ui->block()->plugin()->uri().c_str() % port_index);
+		ui->world().log().error("%1% UI tried to access invalid port %2%\n",
+		                        ui->block()->plugin()->uri().c_str(),
+		                        port_index);
 		return SPtr<const PortModel>();
 	}
 	return ui->block()->ports()[port_index];
@@ -58,8 +58,8 @@ lv2_ui_write(SuilController controller,
 	if (format == 0) {
 		if (buffer_size != 4) {
 			ui->world().log().error(
-				fmt("%1% UI wrote corrupt float with bad size\n")
-				% ui->block()->plugin()->uri().c_str());
+				"%1% UI wrote corrupt float with bad size\n",
+				ui->block()->plugin()->uri().c_str());
 			return;
 		}
 		const float value = *(const float*)buffer;
@@ -83,9 +83,9 @@ lv2_ui_write(SuilController controller,
 		                              val,
 		                              Resource::Graph::DEFAULT);
 	} else {
-		ui->world().log().warn(
-			fmt("Unknown value format %1% from LV2 UI\n")
-			% format % ui->block()->plugin()->uri().c_str());
+		ui->world().log().warn("Unknown value format %1% from LV2 UI\n",
+		                       format,
+		                       ui->block()->plugin()->uri().c_str());
 	}
 }
 
@@ -238,14 +238,14 @@ PluginUI::instantiate()
 		const LilvNode* sym  = lilv_world_get(lworld, note, uris.lv2_symbol, nullptr);
 		const LilvNode* plug = lilv_world_get(lworld, note, ui_plugin, nullptr);
 		if (!plug) {
-			_world.log().error(fmt("%1% UI %2% notification missing plugin\n")
-			                   % plugin_uri % lilv_node_as_string(_ui_node));
+			_world.log().error("%1% UI %2% notification missing plugin\n",
+			                   plugin_uri, lilv_node_as_string(_ui_node));
 		} else if (!sym) {
-			_world.log().error(fmt("%1% UI %2% notification missing symbol\n")
-			                   % plugin_uri % lilv_node_as_string(_ui_node));
+			_world.log().error("%1% UI %2% notification missing symbol\n",
+			                   plugin_uri, lilv_node_as_string(_ui_node));
 		} else if (!lilv_node_is_uri(plug)) {
-			_world.log().error(fmt("%1% UI %2% notification has non-URI plugin\n")
-			                   % plugin_uri % lilv_node_as_string(_ui_node));
+			_world.log().error("%1% UI %2% notification has non-URI plugin\n",
+			                   plugin_uri, lilv_node_as_string(_ui_node));
 		} else if (!strcmp(lilv_node_as_uri(plug), plugin_uri.c_str())) {
 			// Notification is valid and for this plugin
 			uint32_t index = lv2_ui_port_index(this, lilv_node_as_string(sym));
diff --git a/src/gui/App.cpp b/src/gui/App.cpp
index df4159a1..b9b7f7dc 100644
--- a/src/gui/App.cpp
+++ b/src/gui/App.cpp
@@ -323,7 +323,7 @@ App::property_change(const URI&      subject,
 	} else if (key == uris().ingen_maxRunLoad && value.type() == forge().Float) {
 		_max_run_load = value.get<float>();
 	} else {
-		_world.log().warn(fmt("Unknown engine property %1%\n") % key);
+		_world.log().warn("Unknown engine property %1%\n", key);
 		return;
 	}
 
@@ -343,19 +343,18 @@ fraction_label(float f)
 	char           col_str[8];
 	snprintf(col_str, sizeof(col_str), "%02X%02X%02X",
 	         RGBA_R(col), RGBA_G(col), RGBA_B(col));
-	return (fmt("<span color='#%s'>%d%%</span>") % col_str % (f * 100)).str();
+	return fmt("<span color='#%s'>%d%%</span>", col_str, (f * 100));
 }
 
 std::string
 App::status_text() const
 {
-	return (fmt("%2.1f kHz / %.1f ms, %s, %s DSP")
-	        % (_sample_rate / 1e3f)
-	        % (_block_length * 1e3f / (float)_sample_rate)
-	        % ((_n_threads == 1)
-	           ? "1 thread"
-	           : (fmt("%1% threads") % _n_threads).str())
-	        % fraction_label(_max_run_load)).str();
+	return fmt(
+		"%2.1f kHz / %.1f ms, %s, %s DSP",
+		(_sample_rate / 1e3f),
+		(_block_length * 1e3f / (float)_sample_rate),
+		((_n_threads == 1) ? "1 thread" : fmt("%1% threads", _n_threads)),
+		fraction_label(_max_run_load));
 }
 
 void
@@ -470,10 +469,9 @@ App::quit(Gtk::Window* dialog_parent)
 	try {
 		const std::string path = _world.conf().save(
 			_world.uri_map(), "ingen", "gui.ttl", Configuration::GUI);
-		std::cout << (fmt("Saved GUI settings to %1%\n") % path);
+		std::cout << fmt("Saved GUI settings to %1%\n", path);
 	} catch (const std::exception& e) {
-		std::cerr << (fmt("Error saving GUI settings (%1%)\n")
-		              % e.what());
+		std::cerr << fmt("Error saving GUI settings (%1%)\n", e.what());
 	}
 
 	return true;
diff --git a/src/gui/ConnectWindow.cpp b/src/gui/ConnectWindow.cpp
index e2968ea2..369331e2 100644
--- a/src/gui/ConnectWindow.cpp
+++ b/src/gui/ConnectWindow.cpp
@@ -244,7 +244,7 @@ ConnectWindow::connect(bool existing)
 		}
 
 		if (!URI::is_valid(uri_str)) {
-			error((fmt("Invalid socket URI %1%") % uri_str).str());
+			error(fmt("Invalid socket URI %1%", uri_str));
 			return;
 		}
 
diff --git a/src/gui/GraphBox.cpp b/src/gui/GraphBox.cpp
index cb9edf98..a201eca8 100644
--- a/src/gui/GraphBox.cpp
+++ b/src/gui/GraphBox.cpp
@@ -26,6 +26,7 @@
 #include "ingen/Configuration.hpp"
 #include "ingen/Interface.hpp"
 #include "ingen/Log.hpp"
+#include "ingen/fmt.hpp"
 #include "ingen/client/ClientStore.hpp"
 #include "ingen/client/GraphModel.hpp"
 
@@ -220,9 +221,8 @@ GraphBox::init_box(App& app)
 	if (engine_uri == "ingen:/clients/event_writer") {
 		_status_bar->push("Running internal engine", STATUS_CONTEXT_ENGINE);
 	} else {
-		_status_bar->push(
-			(fmt("Connected to %1%") % engine_uri).str(),
-			STATUS_CONTEXT_ENGINE);
+		_status_bar->push(fmt("Connected to %1%", engine_uri),
+		                  STATUS_CONTEXT_ENGINE);
 	}
 
 	_menu_view_messages_window->signal_activate().connect(
@@ -428,7 +428,7 @@ GraphBox::show_status(const ObjectModel* model)
 	} else if ((block = dynamic_cast<const BlockModel*>(model))) {
 		const PluginModel* plugin = dynamic_cast<const PluginModel*>(block->plugin());
 		if (plugin) {
-			msg << ((boost::format(" (%1%)") % plugin->human_name()).str());
+			msg << fmt(" (%1%)", plugin->human_name());
 		}
 		_status_bar->push(msg.str(), STATUS_CONTEXT_HOVER);
 	}
@@ -541,14 +541,12 @@ GraphBox::save_graph(const URI& uri)
 {
 	if (_app->interface()->uri().string().substr(0, 3) == "tcp") {
 		_status_bar->push(
-			(boost::format("Saved %1% to %2% on client")
-			 % _graph->path() % uri).str(),
+			fmt("Saved %1% to %2% on client", _graph->path(), uri),
 			STATUS_CONTEXT_GRAPH);
 		_app->loader()->save_graph(_graph, uri);
 	} else {
 		_status_bar->push(
-			(boost::format("Saved %1% to %2% on server")
-			 % _graph->path() % uri).str(),
+			fmt("Saved %1% to %2% on server", _graph->path(), uri),
 			STATUS_CONTEXT_GRAPH);
 		_app->interface()->copy(_graph->uri(), uri);
 	}
@@ -618,23 +616,22 @@ GraphBox::event_save_as()
 		if (Glib::file_test(filename, Glib::FILE_TEST_IS_DIR)) {
 			if (Glib::file_test(Glib::build_filename(filename, "manifest.ttl"),
 			                    Glib::FILE_TEST_EXISTS)) {
-				confirmed = confirm(
-					(boost::format("<b>The bundle \"%1%\" already exists."
-					               "  Replace it?</b>") % basename).str());
+				confirmed = confirm(fmt("<b>The bundle \"%1%\" already exists."
+				                        "  Replace it?</b>",
+				                        basename));
 			} else {
 				confirmed = confirm(
-					(boost::format("<b>A directory named \"%1%\" already exists,"
-					               "but is not an Ingen bundle.  "
-					               "Save into it anyway?</b>") % basename).str(),
+					fmt("<b>A directory named \"%1%\" already exists,"
+					    "but is not an Ingen bundle.  "
+					    "Save into it anyway?</b>", basename),
 					"This will create at least 2 .ttl files in this directory,"
 					"and possibly several more files and/or directories, recursively.  "
 					"Existing files will be overwritten.");
 			}
 		} else if (Glib::file_test(filename, Glib::FILE_TEST_EXISTS)) {
-			confirmed = confirm(
-				(boost::format("<b>A file named \"%1%\" already exists.  "
-				               "Replace it with an Ingen bundle?</b>")
-				 % basename).str());
+			confirmed = confirm(fmt("<b>A file named \"%1%\" already exists.  "
+			                        "Replace it with an Ingen bundle?</b>",
+			                        basename));
 			if (confirmed) {
 				::g_remove(filename.c_str());
 			}
@@ -703,8 +700,7 @@ GraphBox::event_export_image()
 			}
 		}
 		_view->canvas()->export_image(filename.c_str(), bg_but->get_active());
-		_status_bar->push((boost::format("Rendered %1% to %2%")
-		                   % _graph->path() % filename).str(),
+		_status_bar->push(fmt("Rendered %1% to %2%", _graph->path(), filename),
 		                  STATUS_CONTEXT_GRAPH);
 	}
 }
diff --git a/src/gui/GraphCanvas.cpp b/src/gui/GraphCanvas.cpp
index 47a0abcf..986fefdc 100644
--- a/src/gui/GraphCanvas.cpp
+++ b/src/gui/GraphCanvas.cpp
@@ -421,8 +421,8 @@ GraphCanvas::connection(SPtr<const ArcModel> arc)
 	if (tail && head) {
 		new gui::Arc(*this, arc, tail, head);
 	} else {
-		_app.log().error(fmt("Unable to find ports to connect %1% => %2%\n")
-		                 % arc->tail_path() % arc->head_path());
+		_app.log().error("Unable to find ports to connect %1% => %2%\n",
+		                 arc->tail_path(), arc->head_path());
 	}
 }
 
@@ -442,8 +442,8 @@ GraphCanvas::disconnection(SPtr<const ArcModel> arc)
 			}
 		}
 	} else {
-		_app.log().error(fmt("Unable to find ports to disconnect %1% => %2%\n")
-		                 % arc->tail_path() % arc->head_path());
+		_app.log().error("Unable to find ports to disconnect %1% => %2%\n",
+		                 arc->tail_path(), arc->head_path());
 	}
 }
 
diff --git a/src/gui/GraphTreeWindow.cpp b/src/gui/GraphTreeWindow.cpp
index 2edf8a44..7d00b0f5 100644
--- a/src/gui/GraphTreeWindow.cpp
+++ b/src/gui/GraphTreeWindow.cpp
@@ -205,8 +205,7 @@ GraphTreeWindow::graph_property_changed(const URI&       key,
 			Gtk::TreeModel::Row row = *i;
 			row[_graph_tree_columns.enabled_col] = value.get<int32_t>();
 		} else {
-			_app->log().error(fmt("Unable to find graph %1%\n")
-			                  % graph->path());
+			_app->log().error("Unable to find graph %1%\n", graph->path());
 		}
 	}
 	_enable_signal = true;
@@ -224,8 +223,7 @@ GraphTreeWindow::graph_moved(SPtr<GraphModel> graph)
 		Gtk::TreeModel::Row row = *i;
 		row[_graph_tree_columns.name_col] = graph->symbol().c_str();
 	} else {
-		_app->log().error(fmt("Unable to find graph %1%\n")
-		                  % graph->path());
+		_app->log().error("Unable to find graph %1%\n", graph->path());
 	}
 
 	_enable_signal = true;
diff --git a/src/gui/NodeModule.cpp b/src/gui/NodeModule.cpp
index ae030067..abb9e970 100644
--- a/src/gui/NodeModule.cpp
+++ b/src/gui/NodeModule.cpp
@@ -334,8 +334,8 @@ NodeModule::delete_port_view(SPtr<const PortModel> model)
 	if (p) {
 		delete p;
 	} else {
-		app().log().warn(fmt("Failed to find port %1% on module %2%\n")
-		                 % model->path() % _block->path());
+		app().log().warn("Failed to find port %1% on module %2%\n",
+		                 model->path(), _block->path());
 	}
 }
 
@@ -381,7 +381,7 @@ NodeModule::popup_gui()
 
 			return true;
 		} else {
-			app().log().warn(fmt("No LV2 GUI for %1%\n") % _block->path());
+			app().log().warn("No LV2 GUI for %1%\n", _block->path());
 		}
 	}
 
diff --git a/src/gui/PluginMenu.cpp b/src/gui/PluginMenu.cpp
index e85d1da7..49ee059d 100644
--- a/src/gui/PluginMenu.cpp
+++ b/src/gui/PluginMenu.cpp
@@ -112,8 +112,8 @@ PluginMenu::build_plugin_class_menu(Gtk::Menu*               menu,
 		const char* sub_label_str = lilv_node_as_string(lilv_plugin_class_get_label(c));
 		const char* sub_uri_str   = lilv_node_as_string(lilv_plugin_class_get_uri(c));
 		if (ancestors.find(sub_uri_str) != ancestors.end()) {
-			_world.log().warn(fmt("Infinite LV2 class recursion: %1% <: %2%\n")
-			                  % class_uri_str % sub_uri_str);
+			_world.log().warn("Infinite LV2 class recursion: %1% <: %2%\n",
+			                  class_uri_str, sub_uri_str);
 			return 0;
 		}
 
diff --git a/src/gui/PropertiesWindow.cpp b/src/gui/PropertiesWindow.cpp
index 994ed224..ba25d69b 100644
--- a/src/gui/PropertiesWindow.cpp
+++ b/src/gui/PropertiesWindow.cpp
@@ -359,7 +359,7 @@ PropertiesWindow::create_value_widget(const URI&  key,
 		return widget;
 	}
 
-	_app->log().error(fmt("No widget for value type %1%\n") % type);
+	_app->log().error("No widget for value type %1%\n", type);
 
 	return nullptr;
 }
@@ -453,7 +453,7 @@ PropertiesWindow::get_value(LV2_URID type, Gtk::Widget* value_widget)
 		if (uri_entry && URI::is_valid(uri_entry->get_text())) {
 			return _app->forge().make_urid(URI(uri_entry->get_text()));
 		} else {
-			_app->log().error(fmt("Invalid URI <%1%>\n") % uri_entry->get_text());
+			_app->log().error("Invalid URI <%1%>\n", uri_entry->get_text());
 		}
 	} else if (type == forge.String) {
 		Gtk::Entry* entry = dynamic_cast<Gtk::Entry*>(value_widget);
@@ -480,7 +480,7 @@ PropertiesWindow::on_change(const URI& key)
 	if (value.is_valid()) {
 		record.value = value;
 	} else {
-		_app->log().error(fmt("Failed to get `%1%' value from widget\n") % key);
+		_app->log().error("Failed to get `%1%' value from widget\n", key);
 	}
 }
 
diff --git a/src/gui/RDFS.cpp b/src/gui/RDFS.cpp
index 1ce3618d..80cc24f1 100644
--- a/src/gui/RDFS.cpp
+++ b/src/gui/RDFS.cpp
@@ -132,7 +132,7 @@ types(World& world, SPtr<const client::ObjectModel> model)
 				types.insert(world.uris().lv2_Plugin);
 			}
 		} else {
-			world.log().error(fmt("<%1%> has non-URI type\n") % model->uri());
+			world.log().error("<%1%> has non-URI type\n", model->uri());
 		}
 	}
 
diff --git a/src/gui/WidgetFactory.cpp b/src/gui/WidgetFactory.cpp
index 3ca4eec4..a2a83a6f 100644
--- a/src/gui/WidgetFactory.cpp
+++ b/src/gui/WidgetFactory.cpp
@@ -58,8 +58,8 @@ WidgetFactory::find_ui_file()
 		return;
 	}
 
-	throw std::runtime_error((fmt("Unable to find ingen_gui.ui in %1%\n")
-	                          % INGEN_DATA_DIR).str());
+	throw std::runtime_error(fmt("Unable to find ingen_gui.ui in %1%\n",
+	                             INGEN_DATA_DIR));
 }
 
 Glib::RefPtr<Gtk::Builder>
diff --git a/src/ingen/ingen.cpp b/src/ingen/ingen.cpp
index bc47d433..e5503715 100644
--- a/src/ingen/ingen.cpp
+++ b/src/ingen/ingen.cpp
@@ -143,11 +143,11 @@ main(int argc, char** argv)
 	if (!engine_interface) {
 		const char* const uri = conf.option("connect").ptr<char>();
 		ingen_try(URI::is_valid(uri),
-		          (fmt("Invalid URI <%1%>") % uri).str().c_str());
+		          fmt("Invalid URI <%1%>", uri).c_str());
 		engine_interface = world->new_interface(URI(uri), dummy_client);
 
 		if (!engine_interface && !conf.option("gui").get<int32_t>()) {
-			cerr << (fmt("ingen: error: Failed to connect to `%1%'\n") % uri);
+			cerr << fmt("ingen: error: Failed to connect to `%1%'\n", uri);
 			return EXIT_FAILURE;
 		}
 
@@ -256,7 +256,7 @@ main(int argc, char** argv)
 	// Save configuration to restore preferences on next run
 	const std::string path = conf.save(
 		world->uri_map(), "ingen", "options.ttl", Configuration::GLOBAL);
-	std::cout << (fmt("Saved configuration to %1%") % path) << std::endl;
+	std::cout << fmt("Saved configuration to %1%\n", path);
 
 	engine_interface.reset();
 
diff --git a/src/server/BlockFactory.cpp b/src/server/BlockFactory.cpp
index 02be5159..d5a8e2d3 100644
--- a/src/server/BlockFactory.cpp
+++ b/src/server/BlockFactory.cpp
@@ -165,9 +165,8 @@ BlockFactory::load_lv2_plugins()
 			const char* feature = lilv_node_as_uri(lilv_nodes_get(features, f));
 			if (!_world.lv2_features().is_supported(feature)) {
 				supported = false;
-				_world.log().warn(
-					fmt("Ignoring <%1%>; required feature <%2%>\n")
-					% uri % feature);
+				_world.log().warn("Ignoring <%1%>; required feature <%2%>\n",
+				                  uri, feature);
 				break;
 			}
 		}
@@ -178,8 +177,8 @@ BlockFactory::load_lv2_plugins()
 
 		// Ignore plugins that are missing ports
 		if (!lilv_plugin_get_port_by_index(lv2_plug, 0)) {
-			_world.log().warn(
-				fmt("Ignoring <%1%>; missing or corrupt ports\n") % uri);
+			_world.log().warn("Ignoring <%1%>; missing or corrupt ports\n",
+			                  uri);
 			continue;
 		}
 
@@ -197,10 +196,10 @@ BlockFactory::load_lv2_plugins()
 			    !lilv_port_has_property(lv2_plug,
 			                            port,
 			                            _world.uris().lv2_connectionOptional)) {
-				_world.log().warn(
-					fmt("Ignoring <%1%>; unsupported port <%2%>\n")
-					% uri % lilv_node_as_string(
-						lilv_port_get_symbol(lv2_plug, port)));
+				_world.log().warn("Ignoring <%1%>; unsupported port <%2%>\n",
+				                  uri,
+				                  lilv_node_as_string(
+					                  lilv_port_get_symbol(lv2_plug, port)));
 				break;
 			}
 		}
@@ -217,7 +216,7 @@ BlockFactory::load_lv2_plugins()
 		}
 	}
 
-	_world.log().info(fmt("Loaded %1% plugins\n") % _plugins.size());
+	_world.log().info("Loaded %1% plugins\n", _plugins.size());
 }
 
 } // namespace server
diff --git a/src/server/CompiledGraph.cpp b/src/server/CompiledGraph.cpp
index 073b234e..dec5fdaf 100644
--- a/src/server/CompiledGraph.cpp
+++ b/src/server/CompiledGraph.cpp
@@ -67,11 +67,10 @@ CompiledGraph::compile(Raul::Maid& maid, GraphImpl& graph)
 	} catch (const FeedbackException& e) {
 		Log& log = graph.engine().log();
 		if (e.node && e.root) {
-			log.error(fmt("Feedback compiling %1% from %2%\n")
-			          % e.node->path() % e.root->path());
+			log.error("Feedback compiling %1% from %2%\n",
+			          e.node->path(), e.root->path());
 		} else {
-			log.error(fmt("Feedback compiling %1%\n")
-			          % e.node->path());
+			log.error("Feedback compiling %1%\n", e.node->path());
 		}
 		return MPtr<CompiledGraph>();
 	}
diff --git a/src/server/Engine.cpp b/src/server/Engine.cpp
index c463e7d6..5ab5e490 100644
--- a/src/server/Engine.cpp
+++ b/src/server/Engine.cpp
@@ -509,14 +509,14 @@ Engine::log() const
 void
 Engine::register_client(SPtr<Interface> client)
 {
-	log().info(fmt("Registering client <%1%>\n") % client->uri().c_str());
+	log().info("Registering client <%1%>\n", client->uri().c_str());
 	_broadcaster->register_client(client);
 }
 
 bool
 Engine::unregister_client(SPtr<Interface> client)
 {
-	log().info(fmt("Unregistering client <%1%>\n") % client->uri().c_str());
+	log().info("Unregistering client <%1%>\n", client->uri().c_str());
 	return _broadcaster->unregister_client(client);
 }
 
diff --git a/src/server/JackDriver.cpp b/src/server/JackDriver.cpp
index 35406ec4..6e3ca9d6 100644
--- a/src/server/JackDriver.cpp
+++ b/src/server/JackDriver.cpp
@@ -22,7 +22,6 @@
 #include <jack/midiport.h>
 #ifdef INGEN_JACK_SESSION
 #include <jack/session.h>
-#include <boost/format.hpp>
 #include "ingen/Serialiser.hpp"
 #endif
 #ifdef HAVE_JACK_METADATA
@@ -36,6 +35,7 @@
 #include "ingen/URI.hpp"
 #include "ingen/URIMap.hpp"
 #include "ingen/World.hpp"
+#include "ingen/fmt.hpp"
 #include "lv2/atom/util.h"
 
 #include "Buffer.hpp"
@@ -89,8 +89,8 @@ JackDriver::attach(const std::string& server_name,
 			_client = jack_client_open(client_name.c_str(),
 			                           JackSessionID, nullptr,
 			                           uuid.c_str());
-			_engine.log().info(fmt("Connected to Jack as `%1%' (UUID `%2%')\n")
-			                   % client_name.c_str() % uuid);
+			_engine.log().info("Connected to Jack as `%1%' (UUID `%2%')\n",
+			                   client_name.c_str(), uuid);
 		}
 #endif
 
@@ -99,8 +99,7 @@ JackDriver::attach(const std::string& server_name,
 			if ((_client = jack_client_open(client_name.c_str(),
 			                                JackServerName, nullptr,
 			                                server_name.c_str()))) {
-				_engine.log().info(fmt("Connected to Jack server `%1%'\n")
-				                   % server_name);
+				_engine.log().info("Connected to Jack server `%1%'\n", server_name);
 			}
 		}
 
@@ -171,7 +170,7 @@ JackDriver::activate()
 		_engine.log().error("Could not activate Jack client, aborting\n");
 		return false;
 	} else {
-		_engine.log().info(fmt("Activated Jack client `%1%'\n") %
+		_engine.log().info("Activated Jack client `%1%'\n",
 		                   world.conf().option("jack-name").ptr<char>());
 	}
 	return true;
@@ -545,12 +544,11 @@ JackDriver::_block_length_cb(jack_nframes_t nframes)
 void
 JackDriver::_session_cb(jack_session_event_t* event)
 {
-	_engine.log().info(fmt("Jack session save to %1%\n") % event->session_dir);
+	_engine.log().info("Jack session save to %1%\n", event->session_dir);
 
-	const std::string cmd = (
-		boost::format("ingen -eg -n %1% -u %2% -l ${SESSION_DIR}")
-		% jack_get_client_name(_client)
-		% event->client_uuid).str();
+	const std::string cmd = fmt("ingen -eg -n %1% -u %2% -l ${SESSION_DIR}",
+	                            jack_get_client_name(_client),
+	                            event->client_uuid);
 
 	SPtr<Serialiser> serialiser = _engine.world().serialiser();
 	if (serialiser) {
diff --git a/src/server/LV2Block.cpp b/src/server/LV2Block.cpp
index bf6cbd60..54280b5e 100644
--- a/src/server/LV2Block.cpp
+++ b/src/server/LV2Block.cpp
@@ -84,8 +84,8 @@ LV2Block::make_instance(URIs&      uris,
 		lplug, rate, _features->array());
 
 	if (!inst) {
-		engine.log().error(fmt("Failed to instantiate <%1%>\n")
-		                   % _lv2_plugin->uri().c_str());
+		engine.log().error("Failed to instantiate <%1%>\n",
+		                   _lv2_plugin->uri().c_str());
 		return SPtr<Instance>();
 	}
 
@@ -141,14 +141,15 @@ LV2Block::make_instance(URIs&      uris,
 						port->set_type(PortType::CV, 0);
 					} else {
 						parent_graph()->engine().log().error(
-							fmt("%1% auto-morphed to unknown type %2%\n")
-							% port->path().c_str() % type);
+							"%1% auto-morphed to unknown type %2%\n",
+							port->path().c_str(),
+							type);
 						return SPtr<Instance>();
 					}
 				} else {
 					parent_graph()->engine().log().error(
-						fmt("Failed to get auto-morphed type of %1%\n")
-						% port->path().c_str());
+						"Failed to get auto-morphed type of %1%\n",
+						port->path().c_str());
 				}
 			}
 		}
@@ -304,8 +305,8 @@ LV2Block::instantiate(BufferFactory& bufs, const LilvState* state)
 		uint32_t port_buffer_size = bufs.default_size(buffer_type);
 		if (port_buffer_size == 0 && !optional) {
 			parent_graph()->engine().log().error(
-				fmt("<%1%> port `%2%' has unknown buffer type\n")
-				% _lv2_plugin->uri().c_str() % port_sym.c_str());
+				"<%1%> port `%2%' has unknown buffer type\n",
+				_lv2_plugin->uri().c_str(), port_sym.c_str());
 			ret = false;
 			break;
 		}
@@ -355,8 +356,8 @@ LV2Block::instantiate(BufferFactory& bufs, const LilvState* state)
 		if ((port_type == PortType::UNKNOWN && !optional) ||
 		    direction == UNKNOWN) {
 			parent_graph()->engine().log().error(
-				fmt("<%1%> port `%2%' has unknown type or direction\n")
-				% _lv2_plugin->uri().c_str() % port_sym.c_str());
+				"<%1%> port `%2%' has unknown type or direction\n",
+				_lv2_plugin->uri().c_str(), port_sym.c_str());
 			ret = false;
 			break;
 		}
@@ -563,7 +564,7 @@ LV2Block::work(uint32_t size, const void* data)
 		LV2_Worker_Status st   = _worker_iface->work(inst, work_respond, this, size, data);
 		if (st) {
 			parent_graph()->engine().log().error(
-				fmt("Error calling %1% work method\n") % _path);
+				"Error calling %1% work method\n", _path);
 		}
 		return st;
 	}
diff --git a/src/server/LV2Plugin.cpp b/src/server/LV2Plugin.cpp
index 7012c8fd..9152ab99 100644
--- a/src/server/LV2Plugin.cpp
+++ b/src/server/LV2Plugin.cpp
@@ -128,8 +128,8 @@ LV2Plugin::load_presets()
 				lilv_nodes_free(labels);
 			} else {
 				_world.log().error(
-					fmt("Preset <%1%> has no rdfs:label\n")
-					% lilv_node_as_string(lilv_nodes_get(presets, i)));
+					"Preset <%1%> has no rdfs:label\n",
+					lilv_node_as_string(lilv_nodes_get(presets, i)));
 			}
 		}
 
diff --git a/src/server/RunContext.cpp b/src/server/RunContext.cpp
index d7b96fba..7087b5ab 100644
--- a/src/server/RunContext.cpp
+++ b/src/server/RunContext.cpp
@@ -164,8 +164,8 @@ RunContext::set_priority(int priority)
 		sp.sched_priority = (priority > 0) ? priority : 0;
 		if (pthread_setschedparam(pthread, policy, &sp)) {
 			_engine.log().error(
-				fmt("Failed to set real-time priority of run thread (%s)\n")
-				% strerror(errno));
+				"Failed to set real-time priority of run thread (%s)\n",
+				strerror(errno));
 		}
 	}
 }
diff --git a/src/server/SocketListener.cpp b/src/server/SocketListener.cpp
index bd25d351..849adcad 100644
--- a/src/server/SocketListener.cpp
+++ b/src/server/SocketListener.cpp
@@ -101,25 +101,26 @@ ingen_listen(Engine* engine, Raul::Socket* unix_sock, Raul::Socket* net_sock)
 			const pid_t       pid    = std::stoi(suffix);
 			if (!kill(pid, 0)) {
 				make_link = false;
-				world.log().warn(fmt("Another Ingen instance is running at %1% => %2%\n")
-				                 % link_path % old_path);
+				world.log().warn(
+				        "Another Ingen instance is running at %1% => %2%\n",
+				        link_path, old_path);
 			} else {
-				world.log().warn(fmt("Replacing old link %1% => %2%\n")
-				                 % link_path % old_path);
+				world.log().warn("Replacing old link %1% => %2%\n",
+				                 link_path, old_path);
 				unlink(link_path.c_str());
 			}
 		}
 
 		if (make_link) {
 			if (!symlink(unix_path.c_str(), link_path.c_str())) {
-				world.log().info(fmt("Listening on %1%\n") %
+				world.log().info("Listening on %1%\n",
 				                 (unix_scheme + link_path));
 			} else {
-				world.log().error(fmt("Failed to link %1% => %2% (%3%)\n")
-				                  % link_path % unix_path % strerror(errno));
+				world.log().error("Failed to link %1% => %2% (%3%)\n",
+				                  link_path, unix_path, strerror(errno));
 			}
 		} else {
-			world.log().info(fmt("Listening on %1%\n") % unix_uri);
+			world.log().info("Listening on %1%\n", unix_uri);
 		}
 	}
 
@@ -131,7 +132,7 @@ ingen_listen(Engine* engine, Raul::Socket* unix_sock, Raul::Socket* net_sock)
 		world.log().error("Failed to create TCP socket\n");
 		net_sock->close();
 	} else {
-		world.log().info(fmt("Listening on TCP port %1%\n") % port);
+		world.log().info("Listening on TCP port %1%\n", port);
 	}
 
 	if (unix_sock->fd() == -1 && net_sock->fd() == -1) {
@@ -157,7 +158,7 @@ ingen_listen(Engine* engine, Raul::Socket* unix_sock, Raul::Socket* net_sock)
 		// Wait for input to arrive at a socket
 		const int ret = poll(pfds, nfds, -1);
 		if (ret == -1) {
-			world.log().error(fmt("Poll error: %1%\n") % strerror(errno));
+			world.log().error("Poll error: %1%\n", strerror(errno));
 			break;
 		} else if (ret == 0) {
 			world.log().warn("Poll returned with no data\n");
diff --git a/src/server/events/Delta.cpp b/src/server/events/Delta.cpp
index efc50bce..982b1141 100644
--- a/src/server/events/Delta.cpp
+++ b/src/server/events/Delta.cpp
@@ -127,7 +127,7 @@ Delta::add_set_event(const char* port_symbol,
 	BlockImpl* block = dynamic_cast<BlockImpl*>(_object);
 	PortImpl*  port  = block->port_by_symbol(port_symbol);
 	if (!port) {
-		_engine.log().warn(fmt("Unknown port `%1%' in state") % port_symbol);
+		_engine.log().warn("Unknown port `%1%' in state", port_symbol);
 		return;
 	}
 
@@ -373,7 +373,7 @@ Delta::pre_process(PreProcessContext& ctx)
 							lilv_state_emit_port_values(
 								_state, s_add_set_event, this);
 						} else {
-							_engine.log().warn(fmt("Failed to load preset <%1%>\n") % uri);
+							_engine.log().warn("Failed to load preset <%1%>\n", uri);
 						}
 					} else {
 						_status = Status::BAD_VALUE;
diff --git a/src/server/ingen_lv2.cpp b/src/server/ingen_lv2.cpp
index 2d1769a0..25ead48e 100644
--- a/src/server/ingen_lv2.cpp
+++ b/src/server/ingen_lv2.cpp
@@ -538,8 +538,8 @@ ingen_instantiate(const LV2_Descriptor*    descriptor,
 	}
 
 	plugin->world->log().info(
-		fmt("Block: %1% frames, Sequence: %2% bytes\n")
-		% block_length % seq_size);
+		"Block: %1% frames, Sequence: %2% bytes\n",
+		block_length, seq_size);
 	plugin->world->conf().set(
 		"queue-size",
 		plugin->world->forge().make(std::max(block_length, seq_size) * 4));