diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,7 @@
+## 2.2.2
+
+* Postgresql primary key is Int4, not Int8 [#519](https://github.com/yesodweb/persistent/issues/519)
+
 ## 2.2.1.2
 
 * Allow postgresql-simple 0.5
diff --git a/Database/Persist/Postgresql.hs b/Database/Persist/Postgresql.hs
--- a/Database/Persist/Postgresql.hs
+++ b/Database/Persist/Postgresql.hs
@@ -488,7 +488,7 @@
                             ]
 
 maySerial :: SqlType -> Maybe Text -> Text
-maySerial SqlInt64 Nothing = " SERIAL "
+maySerial SqlInt64 Nothing = " SERIAL8 "
 maySerial sType _ = " " <> showSqlType sType
 
 mayDefault :: Maybe Text -> Text
diff --git a/persistent-postgresql.cabal b/persistent-postgresql.cabal
--- a/persistent-postgresql.cabal
+++ b/persistent-postgresql.cabal
@@ -1,5 +1,5 @@
 name:            persistent-postgresql
-version:         2.2.1.2
+version:         2.2.2
 license:         MIT
 license-file:    LICENSE
 author:          Felipe Lessa, Michael Snoyman <michael@snoyman.com>