diff --git a/servant-foreign/src/Servant/Foreign.hs b/servant-foreign/src/Servant/Foreign.hs
index 78e85a7b..70728a06 100644
--- a/servant-foreign/src/Servant/Foreign.hs
+++ b/servant-foreign/src/Servant/Foreign.hs
@@ -21,8 +21,6 @@ module Servant.Foreign
   , HeaderArg(..)
   , ArgType(..)
   , Req
-  , CommonGeneratorOptions(..)
-  , defCommonGeneratorOptions
   , toValidFunctionName
   , captureArg
   , defReq
@@ -60,41 +58,6 @@ import GHC.Exts (Constraint)
 import GHC.TypeLits
 import Servant.API
 
--- | This structure is used by specific implementations to let you
--- customize the output
-data CommonGeneratorOptions = CommonGeneratorOptions
-  {
-    functionNameBuilder :: FunctionName -> String  -- ^ function generating function names
-  , requestBody :: String                -- ^ name used when a user want to send the request body (to let you redefine it)
-  , successCallback :: String            -- ^ name of the callback parameter when the request was successful
-  , errorCallback :: String              -- ^ name of the callback parameter when the request reported an error
-  , moduleName :: String                 -- ^ namespace on which we define the foreign function (empty mean local var)
-  , urlPrefix :: String                  -- ^ a prefix we should add to the Url in the codegen
-  }
-
--- | Default options.
---
--- @
--- > defCommonGeneratorOptions = CommonGeneratorOptions
--- >   { functionNameBuilder = camelCase
--- >   , requestBody = "body"
--- >   , successCallback = "onSuccess"
--- >   , errorCallback = "onError"
--- >   , moduleName = ""
--- >   , urlPrefix = ""
--- >   }
--- @
-defCommonGeneratorOptions :: CommonGeneratorOptions
-defCommonGeneratorOptions = CommonGeneratorOptions
-  {
-    functionNameBuilder = camelCase
-  , requestBody = "body"
-  , successCallback = "onSuccess"
-  , errorCallback = "onError"
-  , moduleName = ""
-  , urlPrefix = ""
-  }
-
 -- | Function name builder that simply concat each part together
 concatCase :: FunctionName -> String
 concatCase = concat
@@ -233,7 +196,6 @@ defReq :: Req
 defReq = Req defUrl "GET" [] False []
 
 type family Elem (a :: *) (ls::[*]) :: Constraint where
-  Elem a '[] = 'False ~ 'True
   Elem a (a ': list) = ()
   Elem a (b ': list) = Elem a list
 
diff --git a/servant-js/src/Servant/JS/Internal.hs b/servant-js/src/Servant/JS/Internal.hs
index 5363a58b..e502f49a 100644
--- a/servant-js/src/Servant/JS/Internal.hs
+++ b/servant-js/src/Servant/JS/Internal.hs
@@ -1,5 +1,7 @@
 module Servant.JS.Internal
   ( JavaScriptGenerator
+  , CommonGeneratorOptions(..)
+  , defCommonGeneratorOptions
   , AjaxReq
   , jsSegments
   , segmentToStr
@@ -12,9 +14,7 @@ module Servant.JS.Internal
   , (:<|>)(..)
   , (:>)
   , defReq
-  , defCommonGeneratorOptions
   , reqHeaders
-  , CommonGeneratorOptions(..)
   , HasForeign(..)
   , HeaderArg(..)
   , concatCase
@@ -39,6 +39,41 @@ type AjaxReq = Req
 -- generators are available in this package.
 type JavaScriptGenerator = [Req] -> String
 
+-- | This structure is used by specific implementations to let you
+-- customize the output
+data CommonGeneratorOptions = CommonGeneratorOptions
+  {
+    functionNameBuilder :: FunctionName -> String  -- ^ function generating function names
+  , requestBody :: String                -- ^ name used when a user want to send the request body (to let you redefine it)
+  , successCallback :: String            -- ^ name of the callback parameter when the request was successful
+  , errorCallback :: String              -- ^ name of the callback parameter when the request reported an error
+  , moduleName :: String                 -- ^ namespace on which we define the foreign function (empty mean local var)
+  , urlPrefix :: String                  -- ^ a prefix we should add to the Url in the codegen
+  }
+
+-- | Default options.
+--
+-- @
+-- > defCommonGeneratorOptions = CommonGeneratorOptions
+-- >   { functionNameBuilder = camelCase
+-- >   , requestBody = "body"
+-- >   , successCallback = "onSuccess"
+-- >   , errorCallback = "onError"
+-- >   , moduleName = ""
+-- >   , urlPrefix = ""
+-- >   }
+-- @
+defCommonGeneratorOptions :: CommonGeneratorOptions
+defCommonGeneratorOptions = CommonGeneratorOptions
+  {
+    functionNameBuilder = camelCase
+  , requestBody = "body"
+  , successCallback = "onSuccess"
+  , errorCallback = "onError"
+  , moduleName = ""
+  , urlPrefix = ""
+  }
+
 jsSegments :: [Segment] -> String
 jsSegments []  = ""
 jsSegments [x] = "/" ++ segmentToStr x False