diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index f4e5ea84b9..b51eeb087e 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -5365,7 +5365,7 @@ XactLogCommitRecord(TimestampTz commit_time,
 	{
 		XLogRegisterData((char *) (&xl_twophase), sizeof(xl_xact_twophase));
 		if (xl_xinfo.xinfo & XACT_XINFO_HAS_GID)
-			XLogRegisterData((char *) twophase_gid, strlen(twophase_gid));
+			XLogRegisterData((char *) twophase_gid, strlen(twophase_gid) + 1);
 	}
 
 	if (xl_xinfo.xinfo & XACT_XINFO_HAS_ORIGIN)