diff --git a/src/runtime/c/pgf/parser.c b/src/runtime/c/pgf/parser.c
index 5c66edc96..92c689fae 100644
--- a/src/runtime/c/pgf/parser.c
+++ b/src/runtime/c/pgf/parser.c
@@ -273,7 +273,7 @@ pgf_item_sequence(PgfItem* item,
 
 #ifdef PGF_PARSER_DEBUG
 static void
-pgf_print_production_args(PgfPArgs args,
+pgf_print_production_args(PgfPArgs* args,
                           GuOut* out, GuExn* err)
 {
 	size_t n_args = gu_seq_length(args);