diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index dfe2c70..f50fb5c 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -2016,7 +2016,10 @@ RestoreSnapshot(char *start_address)
 	/* Copy SubXIDs, if present. */
 	if (serialized_snapshot->subxcnt > 0)
 	{
-		snapshot->subxip = snapshot->xip + serialized_snapshot->xcnt;
+		if (snapshot->xip == NULL)
+			snapshot->subxip = (TransactionId *) (snapshot + 1);
+		else
+			snapshot->subxip = snapshot->xip + serialized_snapshot->xcnt;
 		memcpy(snapshot->subxip, serialized_xids + serialized_snapshot->xcnt,
 			   serialized_snapshot->subxcnt * sizeof(TransactionId));
 	}