diff --git a/src/test/subscription/t/100_bugs.pl b/src/test/subscription/t/100_bugs.pl
index 17f60a11bb9..bccb73e1fa1 100644
--- a/src/test/subscription/t/100_bugs.pl
+++ b/src/test/subscription/t/100_bugs.pl
@@ -576,10 +576,13 @@ $node_publisher->stop('fast');
 $node_subscriber->stop('fast');
 
 # BUG #18988
-# The BUG involved a deadlock between the DROP SUBSCRIPTION command and the
-# walsender process. This occurred when DROP SUBSCRIPTION attempted to remove
-# a replication slot by connecting to a newly created database whose caches
-# are not yet initialized.
+# The bug happened due to a self-deadlock between the DROP SUBSCRIPTION
+# command and the walsender process for accessing pg_subscription. This
+# occurred when DROP SUBSCRIPTION attempted to remove a replication slot by
+# connecting to a newly created database whose caches are not yet
+# initialized.
+#
+# The bug is fixed by reducing the lock-level during DROP SUBSCRIPTION.
 $node_publisher->start();
 
 $node_publisher->safe_psql(