diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index e03233ae7d0..6e47100d841 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -3394,7 +3394,8 @@ pgstat_read_current_status(void)
 						   NAMEDATALEN * NumBackendStatSlots);
 	localactivity = (char *)
 		MemoryContextAllocHuge(pgStatLocalContext,
-							   pgstat_track_activity_query_size * NumBackendStatSlots);
+							   (Size) pgstat_track_activity_query_size *
+							   (Size) NumBackendStatSlots);
 #ifdef USE_SSL
 	localsslstatus = (PgBackendSSLStatus *)
 		MemoryContextAlloc(pgStatLocalContext,