diff --git a/pkgs/servers/x11/xorg/overrides.nix b/pkgs/servers/x11/xorg/overrides.nix
index 66f74f305494..7073adb85dde 100644
--- a/pkgs/servers/x11/xorg/overrides.nix
+++ b/pkgs/servers/x11/xorg/overrides.nix
@@ -69,7 +69,9 @@ in
   };
 
   libX11 = attrs: attrs // {
-    preConfigure = setMalloc0ReturnsNullCrossCompiling;
+    preConfigure = setMalloc0ReturnsNullCrossCompiling + ''
+      sed 's,^as_dummy.*,as_dummy="\$PATH",' -i configure
+    '';
     postInstall =
       ''
         # Remove useless DocBook XML files.