--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -4927,16 +4927,17 @@ pref("gfx.content.always-paint", false);
 pref("gfx.apitrace.enabled",false);
 #endif
 
 #ifdef MOZ_X11
 #ifdef MOZ_WIDGET_GTK
 pref("gfx.xrender.enabled",false);
 pref("widget.chrome.allow-gtk-dark-theme", false);
 pref("widget.content.allow-gtk-dark-theme", false);
+pref("widget.allow-client-side-decoration", false);
 #endif
 #endif
 
 pref("widget.window-transforms.disabled", false);
 
 #ifdef XP_WIN
 // Whether to disable the automatic detection and use of direct2d.
 pref("gfx.direct2d.disabled", false);