diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index d743fc0b28..6529e737ea 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -225,7 +225,7 @@ static dlist_head pgStatPending = DLIST_STATIC_INIT(pgStatPending);
  * Force the next stats flush to happen regardless of
  * PGSTAT_MIN_INTERVAL. Useful in test scripts.
  */
-static bool pgStatForceNextFlush = false;
+bool pgStatForceNextFlush = false;
 
 /*
  * Force-clear existing snapshot before next use when stats_fetch_consistency
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 2a4c8ef87f..7f60b2834a 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1352,7 +1352,9 @@ pg_stat_get_io(PG_FUNCTION_ARGS)
 	ReturnSetInfo *rsinfo;
 	PgStat_IO  *backends_io_stats;
 	Datum		reset_time;
+	extern bool pgStatForceNextFlush;
 
+	Assert(!pgStatForceNextFlush);
 	InitMaterializedSRF(fcinfo, 0);
 	rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;