diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 8007e205ed..ea8be886ef 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -3829,6 +3829,8 @@ create_grouping_paths(PlannerInfo *root,
 	{
 		int			flags = 0;
 		GroupPathExtraData extra;
+		
+		Assert(gd != NULL);
 
 		/*
 		 * Determine whether it's possible to perform sort-based