diff --git a/Model.hs b/Model.hs
index 693366b..8df0423 100644
--- a/Model.hs
+++ b/Model.hs
@@ -2,10 +2,7 @@ module Model where
 
 import ClassyPrelude.Yesod
 import Database.Persist.Quasi
-import Data.Aeson
-import Data.Hashable (hashUsing)
 import Data.Slug (Slug, SnapSlug)
-import qualified Data.Text as Text
 import Types
 
 -- You can define all of your database entities in the entities file.
@@ -14,28 +11,3 @@ import Types
 -- http://www.yesodweb.com/book/persistent/
 share [mkPersist sqlSettings, mkMigrate "migrateAll"]
     $(persistFileWith lowerCaseSettings "config/models")
-
-
-ghcMajorVersionToText :: GhcMajorVersion -> Text
-ghcMajorVersionToText (GhcMajorVersion major minor)
-  = pack (show major) <> "." <> pack (show minor)
-
-ghcMajorVersionFromText :: Text -> Maybe GhcMajorVersion
-ghcMajorVersionFromText t = case Text.splitOn "." t of
-  [readMay -> Just major, readMay -> Just minor] ->
-    Just $ GhcMajorVersion major minor
-  _ -> Nothing
-
-instance Hashable GhcMajorVersion where
-  hashWithSalt = hashUsing ghcMajorVersionToText
-
-instance Eq GhcMajorVersion where
-  (GhcMajorVersion a b) == (GhcMajorVersion a' b') =
-    a == a' && b == b'
-
-instance FromJSON GhcMajorVersion where
-  parseJSON = withText "GhcMajorVersion" $
-    maybe mzero return . ghcMajorVersionFromText
-
-instance ToJSON GhcMajorVersion where
-  toJSON = toJSON . ghcMajorVersionToText
diff --git a/Types.hs b/Types.hs
index 502baab..4035611 100644
--- a/Types.hs
+++ b/Types.hs
@@ -1,6 +1,7 @@
 module Types where
 
 import ClassyPrelude.Yesod
+import Data.Aeson
 import Data.BlobStore (ToPath (..), BackupToS3 (..))
 import Data.Hashable (hashUsing)
 import Text.Blaze (ToMarkup)
@@ -118,6 +119,40 @@ instance PathPiece StackageExecutable where
     fromPathPiece "stackage-setup.exe" = Just StackageWindowsExecutable
     fromPathPiece _ = Nothing
 
+data GhcMajorVersion = GhcMajorVersion Int Int
+  deriving (Eq)
+
+ghcMajorVersionToText :: GhcMajorVersion -> Text
+ghcMajorVersionToText (GhcMajorVersion a b)
+  = pack (show a) <> "." <> pack (show b)
+
+ghcMajorVersionFromText :: Text -> Maybe GhcMajorVersion
+ghcMajorVersionFromText t = case T.splitOn "." t of
+  [readMay -> Just a, readMay -> Just b] ->
+    Just $ GhcMajorVersion a b
+  _ -> Nothing
+
+instance PersistFieldSql GhcMajorVersion where
+    sqlType = sqlType . liftM ghcMajorVersionToText
+
+instance PersistField GhcMajorVersion where
+    toPersistValue = toPersistValue . ghcMajorVersionToText
+    fromPersistValue v = do
+        t <- fromPersistValueText v
+        case ghcMajorVersionFromText t of
+            Just ver -> return ver
+            Nothing -> Left $ "Cannot convert to GhcMajorVersion: " <> t
+
+instance Hashable GhcMajorVersion where
+  hashWithSalt = hashUsing ghcMajorVersionToText
+
+instance FromJSON GhcMajorVersion where
+  parseJSON = withText "GhcMajorVersion" $
+    maybe mzero return . ghcMajorVersionFromText
+
+instance ToJSON GhcMajorVersion where
+  toJSON = toJSON . ghcMajorVersionToText
+
 
 data SupportedArch
     = Win32
diff --git a/config/models b/config/models
index 3312cc7..acc4aab 100644
--- a/config/models
+++ b/config/models
@@ -132,8 +132,3 @@ Suggested
 UploadProgress
     message Text
     dest Text Maybe
-
-GhcMajorVersion
-    major Int
-    minor Int
-    UniqueGhcMajorVersion major minor