diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 37aaab1338..28b445f560 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -1050,13 +1050,13 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
 	uint32		hashcode = locallock->hashcode;
 	LWLock	   *partitionLock = LockHashPartitionLock(hashcode);
 	PROC_QUEUE *waitQueue = &(lock->waitProcs);
+	SHM_QUEUE  *waitQueuePos;
 	LOCKMASK	myHeldLocks = MyProc->heldLocks;
 	TimestampTz standbyWaitStart = 0;
 	bool		early_deadlock = false;
 	bool		allow_autovacuum_cancel = true;
 	bool		logged_recovery_conflict = false;
 	ProcWaitStatus myWaitStatus;
-	PGPROC	   *proc;
 	PGPROC	   *leader = MyProc->lockGroupLeader;
 	int			i;
 
@@ -1104,13 +1104,16 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
 	 * we are only considering the part of the wait queue before my insertion
 	 * point.
 	 */
-	if (myHeldLocks != 0)
+	if (myHeldLocks != 0 && waitQueue->size > 0)
 	{
 		LOCKMASK	aheadRequests = 0;
+		SHM_QUEUE  *proc_node;
 
-		proc = (PGPROC *) waitQueue->links.next;
+		proc_node = waitQueue->links.next;
 		for (i = 0; i < waitQueue->size; i++)
 		{
+			PGPROC	   *proc = (PGPROC *) proc_node;
+
 			/*
 			 * If we're part of the same locking group as this waiter, its
 			 * locks neither conflict with ours nor contribute to
@@ -1118,7 +1121,7 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
 			 */
 			if (leader != NULL && leader == proc->lockGroupLeader)
 			{
-				proc = (PGPROC *) proc->links.next;
+				proc_node = proc->links.next;
 				continue;
 			}
 			/* Must he wait for me? */
@@ -1153,24 +1156,25 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
 			}
 			/* Nope, so advance to next waiter */
 			aheadRequests |= LOCKBIT_ON(proc->waitLockMode);
-			proc = (PGPROC *) proc->links.next;
+			proc_node = proc->links.next;
 		}
 
 		/*
-		 * If we fall out of loop normally, proc points to waitQueue head, so
-		 * we will insert at tail of queue as desired.
+		 * If we iterated through the whole queue, cur points to the waitQueue
+		 * head, so we will insert at tail of queue as desired.
 		 */
+		waitQueuePos = proc_node;
 	}
 	else
 	{
 		/* I hold no locks, so I can't push in front of anyone. */
-		proc = (PGPROC *) &(waitQueue->links);
+		waitQueuePos = &waitQueue->links;
 	}
 
 	/*
-	 * Insert self into queue, ahead of the given proc (or at tail of queue).
+	 * Insert self into queue, at the position determined above.
 	 */
-	SHMQueueInsertBefore(&(proc->links), &(MyProc->links));
+	SHMQueueInsertBefore(waitQueuePos, &MyProc->links);
 	waitQueue->size++;
 
 	lock->waitMask |= LOCKBIT_ON(lockmode);