diff --git a/gtk2hs-buildtools.cabal b/gtk2hs-buildtools.cabal
--- a/gtk2hs-buildtools.cabal
+++ b/gtk2hs-buildtools.cabal
@@ -1,12 +1,12 @@
+cabal-version:  3.0
 Name:   gtk2hs-buildtools
-Version:        0.13.8.2
-License:        GPL-2
+Version:        0.13.8.3
+License:        GPL-2.0-only
 License-file:   COPYING
 Copyright:      (c) 2001-2010 The Gtk2Hs Team
 Author:         Axel Simon, Duncan Coutts, Manuel Chakravaty
 Maintainer:     gtk2hs-devel@lists.sourceforge.net
 Build-Type:     Simple
-Cabal-Version:  >= 1.10
 Stability:      stable
 homepage:       http://projects.haskell.org/gtk2hs/
 bug-reports:    https://github.com/gtk2hs/gtk2hs/issues
@@ -48,7 +48,7 @@
           build-depends: fail
         if impl(ghc >= 7.7)
           build-depends: hashtables
-        build-tools:     alex >= 3.0.1, happy >= 1.18.9
+        build-tool-depends: alex:alex >= 3.0.1, happy:happy >= 1.18.9
         hs-source-dirs:  src
                          hierarchyGen
                          callbackGen
@@ -68,6 +68,7 @@
                          TypeGen
                          HookGenerator
                          Gtk2HsC2Hs
+        autogen-modules: Paths_gtk2hs_buildtools
         other-modules:   Paths_gtk2hs_buildtools
                          -- gtk2hsC2hs Modules
                          BaseVersion
diff --git a/src/Gtk2HsSetup.hs b/src/Gtk2HsSetup.hs
--- a/src/Gtk2HsSetup.hs
+++ b/src/Gtk2HsSetup.hs
@@ -80,6 +80,9 @@
        (installedUnitId)
 import Distribution.Simple.Compiler (compilerVersion)
 import qualified Distribution.Compat.Graph as Graph
+#if MIN_VERSION_Cabal(3,6,0)
+import Distribution.Utils.Path (getSymbolicPath)
+#endif 
 
 import Control.Applicative ((<$>))
 
@@ -466,7 +469,13 @@
               PD.hsSourceDirs = srcDirs,
               PD.otherModules = othMods
             }}} = do
-  let findModule m = findFileWithExtension [".chs.pp",".chs"] srcDirs
+  let toPath = 
+#if MIN_VERSION_Cabal(3,6,0)
+        getSymbolicPath
+#else 
+        id 
+#endif 
+  let findModule m = findFileWithExtension [".chs.pp",".chs"] (map toPath srcDirs)
                        (joinPath (components m))
   mExpFiles <- mapM findModule expMods
   mOthFiles <- mapM findModule othMods