diff --git a/lib/libc/stdlib/malloc.c b/lib/libc/stdlib/malloc.c
index 8b31252983c9..11e732ff776a 100644
--- a/lib/libc/stdlib/malloc.c
+++ b/lib/libc/stdlib/malloc.c
@@ -1537,6 +1537,7 @@ arena_run_reg_alloc(arena_run_t *run, arena_bin_t *bin)
 	}
 	/* Not reached. */
 	assert(0);
+	return (NULL);
 }
 
 static inline void