diff --git a/nix-eval.cabal b/nix-eval.cabal
--- a/nix-eval.cabal
+++ b/nix-eval.cabal
@@ -2,9 +2,9 @@
 -- see http://haskell.org/cabal/users-guide/
 
 name:                nix-eval
-version:             0.3.3.0
+version:             0.4.1.0
 synopsis:            Evaluate Haskell expressions using Nix to get packages
-description:         Evaluate Haskell expressions using Nix to get packages
+description:         Evaluate Haskell expressions using Nix to get packages.
 homepage:            http://chriswarbo.net/git/nix-eval
 license:             GPL
 license-file:        LICENSE
@@ -27,7 +27,7 @@
                      , Language.Eval
   other-modules:       Paths_nix_eval
   -- other-extensions:    
-  build-depends:       base >=4.8 && < 4.10
+  build-depends:       base >=4.8 && < 4.13
                      , process
                      , strict
                      , hindent >= 4.0
@@ -41,6 +41,6 @@
   main-is:             Main.hs
   build-depends:       base >= 4.7
                      , QuickCheck
-                     , tasty >= 0.7
+                     , tasty >= 0.11.2.1
                      , tasty-quickcheck
                      , nix-eval
diff --git a/src/Language/Eval/Internal.hs b/src/Language/Eval/Internal.hs
--- a/src/Language/Eval/Internal.hs
+++ b/src/Language/Eval/Internal.hs
@@ -145,7 +145,7 @@
 -- | Creates a Nix expression which will use ghcEnvWithPkgs.nix to make a
 --   Haskell environment containing all of the given packages
 mkGhcPkg ps = env ++ " { name = " ++ name ++ "; pkgNames = " ++ args ++ "; }"
-  where env  = "import " ++ show ghcEnvWithPkgsPath
+  where env  = "(import <nixpkgs> {}).callPackage " ++ show ghcEnvWithPkgsPath
         args = "[ " ++ unwords pkgs ++ " ]"
         pkgs = map (\(Pkg p) -> show p) ps
         name = show (pkgsToName ps)
diff --git a/wrapper.sh b/wrapper.sh
--- a/wrapper.sh
+++ b/wrapper.sh
@@ -48,7 +48,7 @@
 # are more specific
 if shouldDebug && command -v hindent > /dev/null
 then
-    debugMsg "Trying hindent on given input:\n\n$INPUT"
+    debugMsg "Trying hindent on given input:\\n\\n$INPUT"
     if command -v timeout > /dev/null
     then
         INPUT=$(echo "$ORIG_INPUT" | timeout 20 hindent --style fundamental) || {
@@ -63,12 +63,12 @@
     fi
 fi
 
-debugMsg "Evaluating:\n\n$INPUT\n---\n"
+debugMsg "Evaluating:\\n\\n$INPUT\\n---\\n"
 
 OUTPUT=$(echo "$INPUT" | $CMD)
 CODE="$?"
 
-debugMsg "Output:\n\n$OUTPUT"
+debugMsg "Output:\\n\\n$OUTPUT"
 
 echo "$OUTPUT"