diff --git a/test/runtests.sh b/test/runtests.sh
index 4a36c237a..3eab0a98f 100755
--- a/test/runtests.sh
+++ b/test/runtests.sh
@@ -106,6 +106,7 @@ user_pref("extensions.zotero.firstRunGuidance", false);
 user_pref("extensions.zotero.firstRun2", false);
 user_pref("extensions.zotero.reportTranslationFailure", false);
 user_pref("extensions.zotero.httpServer.enabled", true);
+user_pref("extensions.zotero.backup.numBackups", 0);
 EOF
 
 # -v flag on Windows makes Firefox process hang