diff --git a/app/scripts/fetch_xulrunner b/app/scripts/fetch_xulrunner
index 819eff8f6a..a4699dee0d 100755
--- a/app/scripts/fetch_xulrunner
+++ b/app/scripts/fetch_xulrunner
@@ -125,6 +125,9 @@ function modify_omni {
     }
     if (!updateAuto) {' modules/UpdateService.jsm
 	
+	# Prevent error during network requests
+	replace_line 'async lazyInit\(\) \{' 'async lazyInit() { if (this.features) return false;' modules/UrlClassifierExceptionListService.jsm
+	
 	replace_line 'pref\("network.captive-portal-service.enabled".+' 'pref("network.captive-portal-service.enabled", false);' greprefs.js
 	replace_line 'pref\("network.connectivity-service.enabled".+' 'pref("network.connectivity-service.enabled", false);' greprefs.js
 	replace_line 'pref\("toolkit.telemetry.server".+' 'pref("toolkit.telemetry.server", "");' greprefs.js