diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 725a308deb..fcbde10529 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -2226,10 +2226,10 @@ XLogWrite(XLogwrtRqst WriteRqst, TimeLineID tli, bool flexible)
 				 */
 				if (track_wal_io_timing)
 				{
-					instr_time	duration;
+					instr_time	end;
 
-					INSTR_TIME_SET_CURRENT(duration);
-					INSTR_TIME_ACCUM_DIFF(PendingWalStats.wal_write_time, duration, start);
+					INSTR_TIME_SET_CURRENT(end);
+					INSTR_TIME_ACCUM_DIFF(PendingWalStats.wal_write_time, end, start);
 				}
 
 				PendingWalStats.wal_write++;
@@ -8252,10 +8252,10 @@ issue_xlog_fsync(int fd, XLogSegNo segno, TimeLineID tli)
 	 */
 	if (track_wal_io_timing)
 	{
-		instr_time	duration;
+		instr_time	end;
 
-		INSTR_TIME_SET_CURRENT(duration);
-		INSTR_TIME_ACCUM_DIFF(PendingWalStats.wal_sync_time, duration, start);
+		INSTR_TIME_SET_CURRENT(end);
+		INSTR_TIME_ACCUM_DIFF(PendingWalStats.wal_sync_time, end, start);
 	}
 
 	PendingWalStats.wal_sync++;