--- a/services/sync/services-sync.js
+++ b/services/sync/services-sync.js
@@ -32,17 +32,21 @@ pref("services.sync.addons.ignoreUserEna
 
 // Comma-delimited list of hostnames to trust for add-on install.
 pref("services.sync.addons.trustedSourceHostnames", "addons.mozilla.org");
 
 pref("services.sync.log.appender.console", "Fatal");
 pref("services.sync.log.appender.dump", "Error");
 pref("services.sync.log.appender.file.level", "Trace");
 pref("services.sync.log.appender.file.logOnError", true);
+#if defined(NIGHTLY_BUILD)
+pref("services.sync.log.appender.file.logOnSuccess", true);
+#else
 pref("services.sync.log.appender.file.logOnSuccess", false);
+#endif
 pref("services.sync.log.appender.file.maxErrorAge", 864000); // 10 days
 pref("services.sync.log.rootLogger", "Debug");
 pref("services.sync.log.logger.addonutils", "Debug");
 pref("services.sync.log.logger.declined", "Debug");
 pref("services.sync.log.logger.service.main", "Debug");
 pref("services.sync.log.logger.status", "Debug");
 pref("services.sync.log.logger.authenticator", "Debug");
 pref("services.sync.log.logger.network.resources", "Debug");