diff --git a/servant-server/servant-server.cabal b/servant-server/servant-server.cabal
index 6c325517..116c0a10 100644
--- a/servant-server/servant-server.cabal
+++ b/servant-server/servant-server.cabal
@@ -53,10 +53,11 @@ library
       , split              >= 0.2  && < 0.3
       , string-conversions >= 0.3  && < 0.4
       , system-filepath    >= 0.4  && < 0.5
+      , filepath           >= 1
       , text               >= 1.2  && < 1.3
       , transformers       >= 0.3  && < 0.5
       , wai                >= 3.0  && < 3.1
-      , wai-app-static     >= 3.0  && < 3.1
+      , wai-app-static     >= 3.0  && < 3.2
       , warp               >= 3.0  && < 3.1
   hs-source-dirs: src
   default-language: Haskell2010
diff --git a/servant-server/src/Servant/Utils/StaticFiles.hs b/servant-server/src/Servant/Utils/StaticFiles.hs
index 07c51173..203c27f3 100644
--- a/servant-server/src/Servant/Utils/StaticFiles.hs
+++ b/servant-server/src/Servant/Utils/StaticFiles.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 -- | This module defines a sever-side handler that lets you serve static files.
 --
 -- - 'serveDirectory' lets you serve anything that lives under a particular
@@ -6,10 +7,13 @@ module Servant.Utils.StaticFiles (
   serveDirectory,
  ) where
 
-import Filesystem.Path.CurrentOS (decodeString)
+import System.FilePath (addTrailingPathSeparator)
 import Network.Wai.Application.Static (staticApp, defaultFileServerSettings)
 import Servant.API.Raw (Raw)
 import Servant.Server (Server)
+#if !MIN_VERSION_wai_app_static(3,1,0)
+import Filesystem.Path.CurrentOS (decodeString)
+#endif
 
 -- | Serve anything under the specified directory as a 'Raw' endpoint.
 --
@@ -32,5 +36,9 @@ import Servant.Server (Server)
 -- handler in the last position, because /servant/ will try to match the handlers
 -- in order.
 serveDirectory :: FilePath -> Server Raw
-serveDirectory documentRoot =
-  staticApp (defaultFileServerSettings (decodeString (documentRoot ++ "/")))
+serveDirectory =
+#if MIN_VERSION_wai_app_static(3,1,0)
+    staticApp . defaultFileServerSettings . addTrailingPathSeparator
+#else
+    staticApp . defaultFileServerSettings . decodeString . addTrailingPathSeparator
+#endif