diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,12 @@
+0.5.1.0
+=======
+
+* Fix instances of `ConvertStorage` that causes #12
+
 0.5.0.0
 =======
 
-* MTL instances for `PersistentBackendT`. Use `liftDB` instead of removed `MonadReader SqlBackend` instance. 
+* MTL instances for `PersistentBackendT`. Use `liftDB` instead of removed `MonadReader SqlBackend` instance.
 
 0.3.2.0
 =======
diff --git a/servant-auth-token-persistent.cabal b/servant-auth-token-persistent.cabal
--- a/servant-auth-token-persistent.cabal
+++ b/servant-auth-token-persistent.cabal
@@ -1,5 +1,5 @@
 name:                servant-auth-token-persistent
-version:             0.5.0.0
+version:             0.5.1.0
 synopsis:            Persistent backend for servant-auth-token server
 description:         Please see README.md
 homepage:            https://github.com/ncrashed/servant-auth-token#readme
@@ -25,7 +25,6 @@
     , aeson-injector          >= 1.0    && < 1.1
     , bytestring              >= 0.10   && < 0.11
     , containers              >= 0.5    && < 0.6
-    , ghc-prim                >= 0.5    && < 0.6
     , monad-control           >= 1.0    && < 1.1
     , mtl                     >= 2.2    && < 2.3
     , persistent              >= 2.2    && < 2.7
diff --git a/src/Servant/Server/Auth/Token/Persistent/Schema.hs b/src/Servant/Server/Auth/Token/Persistent/Schema.hs
--- a/src/Servant/Server/Auth/Token/Persistent/Schema.hs
+++ b/src/Servant/Server/Auth/Token/Persistent/Schema.hs
@@ -1,15 +1,17 @@
-{-# LANGUAGE MagicHash #-}
+{-# LANGUAGE DefaultSignatures, RecordWildCards #-}
 module Servant.Server.Auth.Token.Persistent.Schema where
 
 import Data.Text
 import Data.Time
+import Database.Persist.Sql (Key, SqlBackend, ToBackendKey, fromSqlKey,
+                             toSqlKey)
 import Database.Persist.TH
-import GHC.Generics
-import GHC.Prim
-
-import Servant.API.Auth.Token
+import GHC.Generics         (Generic)
 
-import qualified Servant.Server.Auth.Token.Model as M
+import           Servant.API.Auth.Token
+import           Servant.Server.Auth.Token.Common (ConvertableKey, fromKey,
+                                                   toKey)
+import qualified Servant.Server.Auth.Token.Model  as M
 
 share [mkPersist sqlSettings
      , mkDeleteCascade sqlSettings
@@ -61,19 +63,111 @@
 class ConvertStorage a b | a -> b, b -> a where
   -- | Convert to internal representation
   convertTo   :: b -> a
-  convertTo = unsafeCoerce#
+  default convertTo :: (ToBackendKey SqlBackend r, a ~ Key r, ConvertableKey b) => b -> a
+  convertTo = toSqlKey . fromKey
+
   -- | Convert from internal representation
   convertFrom :: a -> b
-  convertFrom = unsafeCoerce#
+  default convertFrom :: (ToBackendKey SqlBackend r, a ~ Key r, ConvertableKey b) => a -> b
+  convertFrom = toKey . fromSqlKey
 
-instance ConvertStorage UserImpl M.UserImpl
-instance ConvertStorage UserPerm M.UserPerm
-instance ConvertStorage AuthToken M.AuthToken
-instance ConvertStorage UserRestore M.UserRestore
-instance ConvertStorage UserSingleUseCode M.UserSingleUseCode
-instance ConvertStorage AuthUserGroup M.AuthUserGroup
-instance ConvertStorage AuthUserGroupUsers M.AuthUserGroupUsers
-instance ConvertStorage AuthUserGroupPerms M.AuthUserGroupPerms
+instance ConvertStorage UserImpl M.UserImpl where
+  convertTo M.UserImpl{..} =
+    UserImpl { userImplLogin    = userImplLogin
+             , userImplPassword = userImplPassword
+             , userImplEmail    = userImplEmail
+             }
+
+  convertFrom UserImpl{..} =
+    M.UserImpl { userImplLogin    = userImplLogin
+               , userImplPassword = userImplPassword
+               , userImplEmail    = userImplEmail
+               }
+
+instance ConvertStorage UserPerm M.UserPerm where
+  convertTo M.UserPerm{..} =
+    UserPerm { userPermUser       = convertTo userPermUser
+             , userPermPermission = userPermPermission
+             }
+
+  convertFrom UserPerm{..} =
+    M.UserPerm { userPermUser       = convertFrom userPermUser
+               , userPermPermission = userPermPermission
+               }
+
+instance ConvertStorage AuthToken M.AuthToken where
+  convertTo M.AuthToken{..} =
+    AuthToken { authTokenValue  = authTokenValue
+              , authTokenUser   = convertTo authTokenUser
+              , authTokenExpire = authTokenExpire
+              }
+
+  convertFrom AuthToken{..} =
+    M.AuthToken { authTokenValue  = authTokenValue
+                , authTokenUser   = convertFrom authTokenUser
+                , authTokenExpire = authTokenExpire
+                }
+
+instance ConvertStorage UserRestore M.UserRestore where
+  convertTo M.UserRestore{..} =
+    UserRestore { userRestoreValue  = userRestoreValue
+                , userRestoreUser   = convertTo userRestoreUser
+                , userRestoreExpire = userRestoreExpire
+                }
+
+  convertFrom UserRestore{..} =
+    M.UserRestore { userRestoreValue  = userRestoreValue
+                  , userRestoreUser   = convertFrom userRestoreUser
+                  , userRestoreExpire = userRestoreExpire
+                  }
+
+instance ConvertStorage UserSingleUseCode M.UserSingleUseCode where
+  convertTo M.UserSingleUseCode{..} =
+    UserSingleUseCode { userSingleUseCodeValue  = userSingleUseCodeValue
+                      , userSingleUseCodeUser   = convertTo userSingleUseCodeUser
+                      , userSingleUseCodeExpire = userSingleUseCodeExpire
+                      , userSingleUseCodeUsed   = userSingleUseCodeUsed
+                      }
+
+  convertFrom UserSingleUseCode{..} =
+    M.UserSingleUseCode { userSingleUseCodeValue  = userSingleUseCodeValue
+                        , userSingleUseCodeUser   = convertFrom userSingleUseCodeUser
+                        , userSingleUseCodeExpire = userSingleUseCodeExpire
+                        , userSingleUseCodeUsed   = userSingleUseCodeUsed
+                        }
+
+instance ConvertStorage AuthUserGroup M.AuthUserGroup where
+  convertTo M.AuthUserGroup{..} =
+    AuthUserGroup { authUserGroupName   = authUserGroupName
+                  , authUserGroupParent = convertTo <$> authUserGroupParent
+                  }
+
+  convertFrom AuthUserGroup{..} =
+    M.AuthUserGroup { authUserGroupName   = authUserGroupName
+                    , authUserGroupParent = convertFrom <$> authUserGroupParent
+                    }
+
+instance ConvertStorage AuthUserGroupUsers M.AuthUserGroupUsers where
+  convertTo M.AuthUserGroupUsers{..} =
+    AuthUserGroupUsers { authUserGroupUsersGroup = convertTo authUserGroupUsersGroup
+                       , authUserGroupUsersUser  = convertTo authUserGroupUsersUser
+                       }
+
+  convertFrom AuthUserGroupUsers{..} =
+    M.AuthUserGroupUsers { authUserGroupUsersGroup = convertFrom authUserGroupUsersGroup
+                         , authUserGroupUsersUser  = convertFrom authUserGroupUsersUser
+                         }
+
+instance ConvertStorage AuthUserGroupPerms M.AuthUserGroupPerms where
+  convertTo M.AuthUserGroupPerms{..} =
+    AuthUserGroupPerms { authUserGroupPermsGroup      = convertTo authUserGroupPermsGroup
+                       , authUserGroupPermsPermission = authUserGroupPermsPermission
+                       }
+
+  convertFrom AuthUserGroupPerms{..} =
+    M.AuthUserGroupPerms { authUserGroupPermsGroup      = convertFrom authUserGroupPermsGroup
+                         , authUserGroupPermsPermission = authUserGroupPermsPermission
+                         }
 
 instance ConvertStorage UserImplId M.UserImplId
 instance ConvertStorage UserPermId M.UserPermId