diff --git a/src/backend/utils/activity/backend_status.c b/src/backend/utils/activity/backend_status.c
index 722c5acf38..6e734c6caf 100644
--- a/src/backend/utils/activity/backend_status.c
+++ b/src/backend/utils/activity/backend_status.c
@@ -765,7 +765,8 @@ pgstat_read_current_status(void)
 						   NAMEDATALEN * NumBackendStatSlots);
 	localactivity = (char *)
 		MemoryContextAllocHuge(backendStatusSnapContext,
-							   pgstat_track_activity_query_size * NumBackendStatSlots);
+							   (Size) pgstat_track_activity_query_size *
+							   (Size) NumBackendStatSlots);
 #ifdef USE_SSL
 	localsslstatus = (PgBackendSSLStatus *)
 		MemoryContextAlloc(backendStatusSnapContext,