diff --git a/src/backend/executor/nodeMaterial.c b/src/backend/executor/nodeMaterial.c
index 9798bb75365..a5cd9963907 100644
--- a/src/backend/executor/nodeMaterial.c
+++ b/src/backend/executor/nodeMaterial.c
@@ -95,7 +95,7 @@ ExecMaterial(PlanState *pstate)
 			 * to return the one before that, if possible. So do an extra
 			 * fetch.
 			 */
-			if (!tuplestore_advance(tuplestorestate, forward))
+			if (tuplestorestate == NULL || !tuplestore_advance(tuplestorestate, forward))
 				return NULL;	/* the tuplestore must be empty */
 		}
 		eof_tuplestore = false;