diff --git a/storage/mroonga/vendor/groonga/include/groonga/groonga.h b/storage/mroonga/vendor/groonga/include/groonga/groonga.h
index b08403676c0..c5bbfe09f6d 100644
--- a/storage/mroonga/vendor/groonga/include/groonga/groonga.h
+++ b/storage/mroonga/vendor/groonga/include/groonga/groonga.h
@@ -1640,7 +1640,7 @@ GRN_API int grn_charlen(grn_ctx *ctx, const char *str, const char *end);
 GRN_API grn_rc grn_ctx_push(grn_ctx *ctx, grn_obj *obj);
 GRN_API grn_obj *grn_ctx_pop(grn_ctx *ctx);
 
-GRN_API int grn_obj_columns(grn_ctx *ctx, grn_obj *table,
+GRN_API grn_rc grn_obj_columns(grn_ctx *ctx, grn_obj *table,
                             const char *str, unsigned int str_size, grn_obj *res);
 
 GRN_API grn_rc grn_load(grn_ctx *ctx, grn_content_type input_type,