diff --git a/src/backend/executor/execParallel.c b/src/backend/executor/execParallel.c
index 609643dcf94..60aaa822b7e 100644
--- a/src/backend/executor/execParallel.c
+++ b/src/backend/executor/execParallel.c
@@ -410,7 +410,7 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate, int nworkers)
 
 	/* Estimate space for query text. */
 	query_len = strlen(estate->es_sourceText);
-	shm_toc_estimate_chunk(&pcxt->estimator, query_len);
+	shm_toc_estimate_chunk(&pcxt->estimator, query_len + 1);
 	shm_toc_estimate_keys(&pcxt->estimator, 1);
 
 	/* Estimate space for serialized PlannedStmt. */
@@ -478,8 +478,8 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate, int nworkers)
 	 */
 
 	/* Store query string */
-	query_string = shm_toc_allocate(pcxt->toc, query_len);
-	memcpy(query_string, estate->es_sourceText, query_len);
+	query_string = shm_toc_allocate(pcxt->toc, query_len + 1);
+	memcpy(query_string, estate->es_sourceText, query_len + 1);
 	shm_toc_insert(pcxt->toc, PARALLEL_KEY_QUERY_TEXT, query_string);
 
 	/* Store serialized PlannedStmt. */