diff --git a/src/backend/utils/activity/pgstat_wal.c b/src/backend/utils/activity/pgstat_wal.c
index bcaed14d02..6f3bac5d0f 100644
--- a/src/backend/utils/activity/pgstat_wal.c
+++ b/src/backend/utils/activity/pgstat_wal.c
@@ -38,13 +38,18 @@ static WalUsage prevWalUsage;
  *
  * Must be called by processes that generate WAL, that do not call
  * pgstat_report_stat(), like walwriter.
+ *
+ * force=false is the same as nowait=true, and the statistics will
+ * not be flushed if the lock cannot be acquired.
+ * force=true is the same as nowait=false, and waits until the lock
+ * is acquired and ensures that the statistics are flushed.
  */
 void
 pgstat_report_wal(bool force)
 {
-	pgstat_flush_wal(force);
+	pgstat_flush_wal(!force);
 
-	pgstat_flush_io(force);
+	pgstat_flush_io(!force);
 }
 
 /*