diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,9 +2,14 @@
 
 See full history at: <https://github.com/faylang/fay/commits>
 
+#### 0.24.0.4 (2019-12-03)
+
+* Fixes stack nix integration broken.
+
 #### 0.24.0.3 (2019-04-29)
 
 * Dependency updates including GHC-8.6 support.
+* Added stack compatibility.
 
 #### 0.24.0.2
 
diff --git a/fay.cabal b/fay.cabal
--- a/fay.cabal
+++ b/fay.cabal
@@ -1,5 +1,5 @@
 name:                fay
-version:             0.24.0.3
+version:             0.24.0.4
 synopsis:            A compiler for Fay, a Haskell subset that compiles to JavaScript.
 description:         Fay is a proper subset of Haskell which is type-checked
                      with GHC, and compiled to JavaScript. It is lazy, pure, has a Fay monad,
diff --git a/src/Fay/Compiler/Packages.hs b/src/Fay/Compiler/Packages.hs
--- a/src/Fay/Compiler/Packages.hs
+++ b/src/Fay/Compiler/Packages.hs
@@ -12,6 +12,7 @@
 import           GHC.Paths
 import           System.Directory
 import           System.FilePath
+import           System.Environment
 
 -- | Given a configuration, resolve any packages specified to their
 -- data file directories for importing the *.hs sources.
@@ -55,8 +56,9 @@
 describePackage :: Maybe FilePath -> String -> IO String
 describePackage db name = do
   exists <- doesFileExist ghc_pkg
+  stackInNixShell <- fmap isJust (lookupEnv "STACK_IN_NIX_SHELL")
   let command = if exists
-        then if (isInfixOf ".stack" ghc_pkg)
+        then if (isInfixOf ".stack" ghc_pkg || stackInNixShell)
              then "stack"
              else ghc_pkg
         else "ghc-pkg"
@@ -65,7 +67,9 @@
         _       -> []
       args = extraArgs ++ ["describe",name] ++ ["--expand-env-vars", "-v2"]
              ++ ["--package-db=" ++ db' | Just db' <- [db]]
+  when stackInNixShell (unsetEnv "STACK_IN_NIX_SHELL")
   result <- readAllFromProcess command args ""
+  when stackInNixShell (setEnv "STACK_IN_NIX_SHELL" "1")
   case result of
     Left  (err,out) -> error $ "ghc-pkg describe error:\n" ++ err ++ "\n" ++ out
     Right (_err,out) -> return out
diff --git a/src/Fay/Compiler/Typecheck.hs b/src/Fay/Compiler/Typecheck.hs
--- a/src/Fay/Compiler/Typecheck.hs
+++ b/src/Fay/Compiler/Typecheck.hs
@@ -12,6 +12,7 @@
 import qualified GHC.Paths             as GHCPaths
 
 import           System.Directory
+import           System.Environment
 
 -- | Call out to GHC to type-check the file.
 typecheck :: Config -> FilePath -> IO (Either CompileError String)
@@ -40,8 +41,9 @@
           , "-i" ++ intercalate ":" includeDirs
           , fp ] ++ ghcPackageDbArgs ++ wallF ++ map ("-package " ++) packages
   exists <- doesFileExist GHCPaths.ghc
+  stackInNixShell <- fmap isJust (lookupEnv "STACK_IN_NIX_SHELL")
   let ghcPath = if exists
-        then if (isInfixOf ".stack" GHCPaths.ghc)
+        then if (isInfixOf ".stack" GHCPaths.ghc || stackInNixShell)
              then "stack"
              else GHCPaths.ghc
         else "ghc"
@@ -50,7 +52,9 @@
         _       -> []
   when (configShowGhcCalls cfg) $
     putStrLn . unwords $ ghcPath : (extraFlags ++ flags)
+  when stackInNixShell (unsetEnv "STACK_IN_NIX_SHELL")
   res <- readAllFromProcess ghcPath (extraFlags ++ flags) ""
+  when stackInNixShell (setEnv "STACK_IN_NIX_SHELL" "1")
   either (return . Left . GHCError . fst) (return . Right . fst) res
    where
     wallF | configWall cfg = ["-Wall"]