diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index b603700ed9..ce8eddf640 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -2294,7 +2294,7 @@
   proname => 'to_timestamp', prorettype => 'timestamptz',
   proargtypes => 'float8', prosrc => 'float8_timestamptz' },
 { oid => '1159', descr => 'adjust timestamp to new time zone',
-  proname => 'timezone', prorettype => 'timestamp',
+  proname => 'timezone', provolatile => 's', prorettype => 'timestamp',
   proargtypes => 'text timestamptz', prosrc => 'timestamptz_zone' },
 
 { oid => '1160', descr => 'I/O',
@@ -6048,7 +6048,7 @@
   prosrc => 'see system_functions.sql' },
 
 { oid => '2069', descr => 'adjust timestamp to new time zone',
-  proname => 'timezone', prorettype => 'timestamptz',
+  proname => 'timezone', provolatile => 's', prorettype => 'timestamptz',
   proargtypes => 'text timestamp', prosrc => 'timestamp_zone' },
 { oid => '2070', descr => 'adjust timestamp to new time zone',
   proname => 'timezone', prorettype => 'timestamptz',