1 files changed, 1 insertions, 0 deletions
diff --git a/grammar.c b/grammar.c
index 01168af..e9ea4b4 100644
--- a/grammar.c
+++ b/grammar.c
@@ -67,6 +67,7 @@ vm_op_t *lookup(def_t *defs, const char *name)
 //
 // Push a backreference onto the backreference stack
 //
+__attribute__((nonnull))
 static def_t *with_backref(def_t *defs, file_t *f, const char *name, match_t *m)
 {
     vm_op_t *op = new(vm_op_t);