diff --git a/pkgs/development/libraries/ilbc/default.nix b/pkgs/development/libraries/ilbc/default.nix
index 4450c6e6ef7..3ab4e7e738c 100644
--- a/pkgs/development/libraries/ilbc/default.nix
+++ b/pkgs/development/libraries/ilbc/default.nix
@@ -4,8 +4,9 @@ stdenv.mkDerivation rec {
   name = "ilbc-rfc3951";
 
   script = fetchurl {
-    url = http://ilbcfreeware.org/documentation/extract-cfile.awk;
-    sha256 = "155izy7p7azak1h6bgafvh84b1605zyw14k2s4pyl5nd4saap5c6";
+    url = http://ilbcfreeware.org/documentation/extract-cfile.txt;
+    name = "extract-cfile.awk";
+    sha256 = "0md76qlszaras9grrxaq7xfxn1yikmz4qqgnjj6y50jg31yr5wyd";
   };
 
   rfc3951 = fetchurl {