--- a/testing/profiles/prefs_general.js
+++ b/testing/profiles/prefs_general.js
@@ -389,8 +389,11 @@ user_pref("marionette.prefs.recommended"
 // Disable Screenshots by default for now
 user_pref("extensions.screenshots.disabled", true);
 
 // Set places maintenance far in the future (the maximum time possible in an
 // int32_t) to avoid it kicking in during tests. The maintenance can take a
 // relatively long time which may cause unnecessary intermittents and slow down
 // tests. This, like many things, will stop working correctly in 2038.
 user_pref("places.database.lastMaintenance", 2147483647);
+
+// Disable Bookmark backups by default.
+user_pref("browser.bookmarks.max_backups", 0);