diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index 7c2e1e1c85421b1a82633088c99bd9080107ecbb..fb39bdc2f598f2af15ebbca8d8f77348472f7702 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -1493,7 +1493,8 @@ GetMaxSnapshotSubxidCount(void)
  *			older than this are known not running any more.
  *		RecentGlobalXmin: the global xmin (oldest TransactionXmin across all
  *			running transactions, except those running LAZY VACUUM).  This is
- *			the same computation done by GetOldestXmin(true, true).
+ *			the same computation done by
+ *			GetOldestXmin(NULL, PROCARRAY_FLAGS_VACUUM).
  *		RecentGlobalDataXmin: the global xmin for non-catalog tables
  *			>= RecentGlobalXmin
  *