diff --git a/pkgs/development/tools/parsing/flex/builder.sh b/pkgs/development/tools/parsing/flex/builder.sh
deleted file mode 100644
index 03bddded882..00000000000
--- a/pkgs/development/tools/parsing/flex/builder.sh
+++ /dev/null
@@ -1,10 +0,0 @@
-. $stdenv/setup
-
-installPhase() {
-   make install
-   cd $out/bin; ln -s flex lex
-   cd $out/lib; ln -s libfl.a libl.a
-}
-
-installPhase=installPhase
-genericBuild
diff --git a/pkgs/development/tools/parsing/flex/default.nix b/pkgs/development/tools/parsing/flex/default.nix
index 24303fd6a53..c386c2be476 100644
--- a/pkgs/development/tools/parsing/flex/default.nix
+++ b/pkgs/development/tools/parsing/flex/default.nix
@@ -4,7 +4,6 @@ assert yacc != null;
 
 stdenv.mkDerivation {
   name = "flex-2.5.4a";
-  builder = ./builder.sh;
   src = fetchurl {
     url = http://catamaran.labs.cs.uu.nl/dist/tarballs/flex-2.5.4a.tar.gz;
     md5 = "bd8753d0b22e1f4ec87a553a73021adf";