diff --git a/pkgs/development/tools/parsing/flex/2.5.39.nix b/pkgs/development/tools/parsing/flex/default.nix
similarity index 75%
rename from pkgs/development/tools/parsing/flex/2.5.39.nix
rename to pkgs/development/tools/parsing/flex/default.nix
index 93d54803e7c7..57ce29f51753 100644
--- a/pkgs/development/tools/parsing/flex/2.5.39.nix
+++ b/pkgs/development/tools/parsing/flex/default.nix
@@ -1,11 +1,11 @@
 { stdenv, fetchurl, bison, m4 }:
 
-stdenv.mkDerivation {
-  name = "flex-2.5.39";
+stdenv.mkDerivation rec {
+  name = "flex-2.6.0";
 
   src = fetchurl {
-    url = mirror://sourceforge/flex/flex-2.5.39.tar.bz2;
-    sha256 = "0zv15giw3gma03y2bzw78hjfy49vyir7vbcgnh9bb3637dgvblmd";
+    url = "mirror://sourceforge/flex/${name}.tar.bz2";
+    sha256 = "1sdqx63yadindzafrq1w31ajblf9gl1c301g068s20s7bbpi3ri4";
   };
 
   buildInputs = [ bison ];
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 8fcc8a6b4193..e1d494c8abc0 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -5613,8 +5613,7 @@ let
   jdepend = callPackage ../development/tools/analysis/jdepend { };
 
   flex_2_5_35 = callPackage ../development/tools/parsing/flex/2.5.35.nix { };
-  flex_2_5_39 = callPackage ../development/tools/parsing/flex/2.5.39.nix { };
-  flex = flex_2_5_39;
+  flex = callPackage ../development/tools/parsing/flex/default.nix { };
 
   flexcpp = callPackage ../development/tools/parsing/flexc++ { };