diff --git a/pkgs/development/tools/parsing/flex/2.6.1.nix b/pkgs/development/tools/parsing/flex/2.6.1.nix
deleted file mode 100644
index aeb141649772..000000000000
--- a/pkgs/development/tools/parsing/flex/2.6.1.nix
+++ /dev/null
@@ -1,36 +0,0 @@
-{ lib, stdenv, fetchurl, bison, m4 }:
-
-stdenv.mkDerivation {
-  name = "flex-2.6.1";
-
-  src = fetchurl {
-    url = "https://github.com/westes/flex/releases/download/v2.6.1/flex-2.6.1.tar.gz";
-    sha256 = "0fy14c35yz2m1n1m4f02by3501fn0cca37zn7jp8lpp4b3kgjhrw";
-  };
-
-  postPatch = ''
-    patchShebangs tests
-  '' + lib.optionalString (stdenv.hostPlatform != stdenv.buildPlatform) ''
-    substituteInPlace Makefile.in --replace "tests" " ";
-  '';
-
-  buildInputs = [ bison ];
-
-  propagatedBuildInputs = [ m4 ];
-
-  preConfigure = lib.optionalString (stdenv.hostPlatform != stdenv.buildPlatform) ''
-    ac_cv_func_malloc_0_nonnull=yes
-    ac_cv_func_realloc_0_nonnull=yes
-  '';
-
-  postConfigure = lib.optionalString (stdenv.isDarwin || stdenv.isCygwin) ''
-    sed -i Makefile -e 's/-no-undefined//;'
-  '';
-
-  meta = with lib; {
-    homepage = "https://github.com/westes/flex";
-    description = "A fast lexical analyser generator";
-    license = licenses.bsd2;
-    platforms = platforms.unix;
-  };
-}