diff --git a/servant-csharp.cabal b/servant-csharp.cabal
--- a/servant-csharp.cabal
+++ b/servant-csharp.cabal
@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                servant-csharp
-version:             0.0.8.0
+version:             0.0.8.1
 synopsis:            Generate servant client library for C#
 description:         Generate servant client library for C#
 homepage:            https://github.com/cutsea110/servant-csharp.git
@@ -37,7 +37,6 @@
                      , bytestring >=0.10 && <0.11
                      , directory >=1.2 && <1.3
                      , filepath >=1.4 && <1.5
-                     , haskell-src-exts >=1.17 && <1.18
                      , heredocs >=0.1 && <0.2
                      , http-types >=0.9 && <0.10
                      , lens >=4.13 && <4.14
diff --git a/src/CS/Common.hs b/src/CS/Common.hs
--- a/src/CS/Common.hs
+++ b/src/CS/Common.hs
@@ -11,6 +11,7 @@
 import Data.Time (UTCTime)
 import Data.Time.Calendar (Day)
 import Data.Typeable
+import Data.Word
 import Servant.Foreign
 
 data CSharp
@@ -18,6 +19,9 @@
 instance HasForeignType CSharp Text a => HasForeignType CSharp Text [a] where
     typeFor lang ftype (Proxy :: Proxy [t]) = "List<" <> typeFor lang ftype (Proxy :: Proxy t) <> ">"
 
+instance HasForeignType CSharp Text a => HasForeignType CSharp Text (Maybe [a]) where
+    typeFor lang ftype (Proxy :: Proxy (Maybe [t])) = typeFor lang ftype (Proxy :: Proxy [t])
+
 instance HasForeignType CSharp Text a => HasForeignType CSharp Text (Maybe a) where
     typeFor lang ftype (Proxy :: Proxy (Maybe t)) = "Nullable<" <> typeFor lang ftype (Proxy :: Proxy t) <> ">"
 
@@ -28,6 +32,32 @@
     typeFor _ _ _ = "int"
 instance {-# OVERLAPPING #-} HasForeignType CSharp Text (Maybe Int) where
     typeFor _ _ _ = "int?"
+instance {-# OVERLAPPING #-} HasForeignType CSharp Text Word8 where
+    typeFor _ _ _ = "int"
+instance {-# OVERLAPPING #-} HasForeignType CSharp Text (Maybe Word8) where
+    typeFor _ _ _ = "int?"
+instance {-# OVERLAPPING #-} HasForeignType CSharp Text Word16 where
+    typeFor _ _ _ = "int"
+instance {-# OVERLAPPING #-} HasForeignType CSharp Text (Maybe Word16) where
+    typeFor _ _ _ = "int?"
+instance {-# OVERLAPPING #-} HasForeignType CSharp Text Word32 where
+    typeFor _ _ _ = "int"
+instance {-# OVERLAPPING #-} HasForeignType CSharp Text (Maybe Word32) where
+    typeFor _ _ _ = "int?"
+instance {-# OVERLAPPING #-} HasForeignType CSharp Text Word64 where
+    typeFor _ _ _ = "int"
+instance {-# OVERLAPPING #-} HasForeignType CSharp Text (Maybe Word64) where
+    typeFor _ _ _ = "int?"
+
+instance {-# OVERLAPPING #-} HasForeignType CSharp Text Float where
+    typeFor _ _ _ = "float"
+instance {-# OVERLAPPING #-} HasForeignType CSharp Text (Maybe Float) where
+    typeFor _ _ _ = "float?"
+
+instance {-# OVERLAPPING #-} HasForeignType CSharp Text Double where
+    typeFor _ _ _ = "double"
+instance {-# OVERLAPPING #-} HasForeignType CSharp Text (Maybe Double) where
+    typeFor _ _ _ = "double?"
 
 instance {-# OVERLAPPING #-} HasForeignType CSharp Text Text where
     typeFor _ _ _ = "string"
diff --git a/src/CS/JsonDotNet.hs b/src/CS/JsonDotNet.hs
--- a/src/CS/JsonDotNet.hs
+++ b/src/CS/JsonDotNet.hs
@@ -36,7 +36,8 @@
 import Data.Swagger hiding (namespace)
 import Data.Text as T (Text, unpack)
 import Data.Time.Clock (UTCTime(..), getCurrentTime)
-import Data.Time.Calendar (toGregorian)
+import Data.Time.Calendar (Day(..), toGregorian)
+import Data.Word
 import System.Directory (createDirectoryIfMissing)
 import System.FilePath ((</>),(<.>))
 import Data.UUID.Types (toString, UUID)
@@ -45,7 +46,7 @@
 import Servant.Swagger
 import Text.Heredoc
 
-import CS.Common (CSharp, getEndpoints)
+import CS.Common
 import CS.JsonDotNet.Internal
 import CS.JsonDotNet.Base
 
@@ -76,6 +77,7 @@
 generateCsForAPI conf api = do
   let outDir = "gen" </> namespace conf
       swagger = toSwagger api
+  createDirectoryIfMissing True $ outDir </> "Properties"
   writeFile (outDir </> "AssemblyInfo.cs") =<< assemblyInfoCs conf
   writeFile (outDir </> namespace conf <.> "csproj") =<< projectCsproj conf
   writeFile (outDir </> classCsName conf)