diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index b5f27b0463c..565d0e70768 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1455,9 +1455,9 @@ pgstat_get_io_time_index(IOOp io_op)
 }
 
 static inline double
-pg_stat_us_to_ms(PgStat_Counter val_ms)
+pg_stat_us_to_ms(PgStat_Counter val_us)
 {
-	return (double) val_ms / 1000.0;
+	return (double) val_us / 1000.0;
 }
 
 /*