diff --git a/pkgs/servers/x11/xorg/overrides.nix b/pkgs/servers/x11/xorg/overrides.nix
index f1b0f64f02e..eb32b83a53e 100644
--- a/pkgs/servers/x11/xorg/overrides.nix
+++ b/pkgs/servers/x11/xorg/overrides.nix
@@ -186,4 +186,8 @@ in
     '';
   };
 
+  twm = attrs: attrs // {
+    buildNativeInputs = [args.bison args.flex];
+  };
+
 }
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index d59cbb19a23..1fa16d5ccfb 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -4577,7 +4577,7 @@ let
     inherit fetchurl fetchsvn stdenv pkgconfig freetype fontconfig
       libxslt expat libdrm libpng zlib perl mesa
       xkeyboard_config dbus hal libuuid openssl gperf m4
-      autoconf libtool xmlto asciidoc udev;
+      autoconf libtool xmlto asciidoc udev bison flex;
 
     # XXX: Update to newer Automake on the next big rebuild; better yet:
     # remove the dependency on Automake.