1 files changed, 3 insertions, 0 deletions
diff --git a/src/filter.c b/src/filter.c
index 6d5e5a04..e5e8fa29 100644
--- a/src/filter.c
+++ b/src/filter.c
@@ -16,6 +16,7 @@
 
 #include "serd/serd.h"
 
+#include <assert.h>
 #include <stdbool.h>
 #include <stdlib.h>
 
@@ -76,6 +77,8 @@ serd_filter_new(const SerdSink* const target,
                 const SerdNode* const graph,
                 const bool            inclusive)
 {
+  assert(target);
+
   SerdFilterData* const data =
     (SerdFilterData*)calloc(1, sizeof(SerdFilterData));