diff --git a/firefox.js b/firefox.js
index 652956a..42ee854 100644
--- a/firefox.js
+++ b/firefox.js
@@ -4,6 +4,7 @@
 // Theme
 user_pref("extensions.activeThemeID", "default-theme@mozilla.org");
 user_pref("devtools.theme", "dark");
+user_pref("ui.systemUsesDarkTheme", 0);
 
 // Ensure context menus stay open after left-click (useful when scale
 // == 1.5)