diff --git a/pkgs/development/compilers/ghc/8.6.3.nix b/pkgs/development/compilers/ghc/8.6.3.nix
index c57e4d96ae2e..605e442553d0 100644
--- a/pkgs/development/compilers/ghc/8.6.3.nix
+++ b/pkgs/development/compilers/ghc/8.6.3.nix
@@ -153,7 +153,7 @@ stdenv.mkDerivation (rec {
   configureFlags = [
     "--datadir=$doc/share/doc/ghc"
     "--with-curses-includes=${ncurses.dev}/include" "--with-curses-libraries=${ncurses.out}/lib"
-  ] ++ stdenv.lib.optionals (libffi != null) ["--with-system-libffi" "--with-ffi-includes=${libffi}/include" "--with-ffi-libraries=${libffi}/lib"
+  ] ++ stdenv.lib.optionals (libffi != null) ["--with-system-libffi" "--with-ffi-includes=${libffi.dev}/include" "--with-ffi-libraries=${libffi.out}/lib"
   ] ++ stdenv.lib.optional (targetPlatform == hostPlatform && !enableIntegerSimple) [
     "--with-gmp-includes=${targetPackages.gmp.dev}/include" "--with-gmp-libraries=${targetPackages.gmp.out}/lib"
   ] ++ stdenv.lib.optional (targetPlatform == hostPlatform && hostPlatform.libc != "glibc" && !targetPlatform.isWindows) [