diff --git a/src/backend/access/heap/README.tuplock b/src/backend/access/heap/README.tuplock
index 030f6ac..562dbf7 100644
--- a/src/backend/access/heap/README.tuplock
+++ b/src/backend/access/heap/README.tuplock
@@ -99,12 +99,13 @@ figure out whether the update committed or aborted.  So we have a requirement
 that pg_multixact needs to retain pages of its data until we're certain that
 the MultiXacts in them are no longer of interest.
 
-VACUUM is in charge of removing old MultiXacts at the time of tuple freezing.
-This works in the same way that pg_clog segments are removed: we have a
-pg_class column that stores the earliest multixact that could possibly be
-stored in the table; the minimum of all such values is stored in a pg_database
-column.  VACUUM computes the minimum across all pg_database values, and
-removes pg_multixact segments older than the minimum.
+The checkpointer is in charge of removing old MultiXacts at the end of a
+checkpoint. This works in the same way that pg_clog segments are removed: we
+have a pg_class column that stores the earliest multixact that could possibly
+be stored in the table; the minimum of all such values is stored in a
+pg_database column.  VACUUM computes the minimum across all pg_database
+values, and sets shared memory state so that the next checkpoint removes
+pg_multixact segments older than the minimum.
 
 Infomask Bits
 -------------