diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 10e394625889..d8584da7d3c9 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -2658,7 +2658,7 @@ let
     inherit fetchurl stdenv unzip;
   };
 
-  flex = flex2535;
+  flex = flex254a;
 
   flex2535 = import ../development/tools/parsing/flex/flex-2.5.35.nix {
     inherit fetchurl stdenv yacc m4;