diff --git a/pkgs/development/tools/parsing/flex/default.nix b/pkgs/development/tools/parsing/flex/default.nix
index 2cd01a28276a..efaed6e459f5 100644
--- a/pkgs/development/tools/parsing/flex/default.nix
+++ b/pkgs/development/tools/parsing/flex/default.nix
@@ -5,7 +5,7 @@ assert yacc != null;
 stdenv.mkDerivation {
   name = "flex-2.5.4a";
   src = fetchurl {
-    url = ftp://ftp.nluug.nl/pub/gnu/flex/flex-2.5.4a.tar.gz;
+    url = ftp://ftp.nluug.nl/pub/gnu/non-gnu/flex/flex-2.5.4a.tar.gz;
     md5 = "bd8753d0b22e1f4ec87a553a73021adf";
   };
   buildInputs = [yacc];