diff --git a/pkgs/by-name/ge/gencfsm/package.nix b/pkgs/by-name/ge/gencfsm/package.nix
index b1c2ae57305c..45342fcbe823 100644
--- a/pkgs/by-name/ge/gencfsm/package.nix
+++ b/pkgs/by-name/ge/gencfsm/package.nix
@@ -29,6 +29,11 @@ stdenv.mkDerivation rec {
     sha256 = "RXVwg/xhfAQv3pWp3UylOhMKDh9ZACTuKM4lPrn1dk8=";
   };
 
+  env.NIX_CFLAGS_COMPILE = toString [
+    # tools.c:38:5: error: implicit declaration of function 'gnome_encfs_manager_on_logout' []
+    "-Wno-implicit-function-declaration"
+  ];
+
   nativeBuildInputs = [
     autoconf
     automake