diff --git a/Setup.hs b/Setup.hs
--- a/Setup.hs
+++ b/Setup.hs
@@ -68,5 +68,5 @@
         needsMove <- doesDirectoryExist (dirName ++ "/package")
         when needsMove $ do
             renameDirectory (dirName ++ "/package") "tempdir"
-            removeDirectory dirName
+            removeDirectoryRecursive dirName
             renameDirectory "tempdir" dirName
diff --git a/fast-arithmetic.cabal b/fast-arithmetic.cabal
--- a/fast-arithmetic.cabal
+++ b/fast-arithmetic.cabal
@@ -1,5 +1,5 @@
 name:                fast-arithmetic
-version:             0.1.0.4
+version:             0.1.0.5
 synopsis:            Fast number-theoretic functions.
 description:         Fast number-theoretic code with a high level of safety guaranteed by ATS.
 homepage:            https://github.com/vmchale/fast-arithmetic#readme
@@ -25,7 +25,7 @@
 }
 
 custom-setup
-  -- ghc-options:     -threaded -rtsopts -with-rtsopts=-N
+  --ghc-options:     -threaded -rtsopts -with-rtsopts=-N
   setup-depends:   base
                  , Cabal >= 2.0
                  , http-client