diff --git a/Web/Routes/Happstack.hs b/Web/Routes/Happstack.hs
--- a/Web/Routes/Happstack.hs
+++ b/Web/Routes/Happstack.hs
@@ -27,21 +27,45 @@
 
 instance (Happstack m) => Happstack (RouteT url m)
 
-implSite :: (Functor m, Monad m, MonadPlus m, ServerMonad m) => String -> FilePath -> Site url (m a) -> m a
+-- | convert a 'Site' to a normal Happstack route
+--
+-- calls 'mzero' if the route can be decoded.
+--
+-- see also: 'implSite_'
+implSite :: (Functor m, Monad m, MonadPlus m, ServerMonad m) => 
+            String         -- ^ "http://example.org"
+         -> FilePath       -- ^ path to this handler, .e.g. "/route/"
+         -> Site url (m a) -- ^ the 'Site'
+         -> m a
 implSite domain approot siteSpec =
   do r <- implSite_ domain approot siteSpec
      case r of
        (Left _) -> mzero
        (Right a) -> return a
 
-implSite_ :: (Functor m, Monad m, MonadPlus m, ServerMonad m) => String -> FilePath -> Site url (m a) -> m (Either String a)
+-- | convert a 'Site' to a normal Happstack route
+--
+-- If url decoding fails, it returns @Left "the parse error"@,
+-- otherwise @Right a@.
+--
+-- see also: 'implSite'
+implSite_ :: (Functor m, Monad m, MonadPlus m, ServerMonad m) => 
+             String          -- ^ "http://example.org"
+          -> FilePath        -- ^ path to this handler, .e.g. "/route/"
+          -> Site url (m a)  -- ^ the 'Site'
+          -> m (Either String a) 
 implSite_ domain approot siteSpec =
     dirs approot $ do rq <- askRq
-                      let pathInfo = intercalate "/" (rqPaths rq)
+                      let pathInfo = intercalate "/" (map escapeSlash (rqPaths rq))
                           f        = runSite (domain ++ approot) siteSpec pathInfo
                       case f of
                         (Left parseError) -> return (Left parseError)
                         (Right sp)   -> Right <$> (localRq (const $ rq { rqPaths = [] }) sp)
+        where
+          escapeSlash :: String -> String
+          escapeSlash [] = []
+          escapeSlash ('/':cs) = "%2F" ++ escapeSlash cs
+          escapeSlash (c:cs)   = c : escapeSlash cs
 {- 
 implSite__ :: (Monad m) => String -> FilePath -> ([ErrorMsg] -> ServerPartT m a) -> Site url (ServerPartT m a) -> (ServerPartT m a)
 implSite__ domain approot handleError siteSpec =
@@ -52,6 +76,7 @@
                         (Failure errs) -> handleError errs
                         (Success sp)   -> localRq (const $ rq { rqPaths = [] }) sp
 -}
+
 -- | similar to 'seeOther' but takes a 'URL' 'm' as an argument
 seeOtherURL :: (ShowURL m, FilterMonad Response m) => URL m -> m Response
 seeOtherURL url = 
diff --git a/web-routes-happstack.cabal b/web-routes-happstack.cabal
--- a/web-routes-happstack.cabal
+++ b/web-routes-happstack.cabal
@@ -1,5 +1,5 @@
 Name:             web-routes-happstack
-Version:          0.22.1
+Version:          0.22.2
 License:          BSD3
 License-File:     LICENSE
 Author:           jeremy@seereason.com