diff --git a/lib/isc/mem.c b/lib/isc/mem.c
index 863dfedae6..693daa7cdf 100644
--- a/lib/isc/mem.c
+++ b/lib/isc/mem.c
@@ -151,7 +151,7 @@ default_memalloc(void *arg, size_t size) {
 static void
 default_memfree(void *arg, void *ptr) {
 	(void)arg;
-	return (free(ptr));
+	free(ptr);
 }
 
 /* Public. */