diff --git a/lib/log4js.js b/lib/log4js.js
index 9d6209b..fdd48c8 100644
--- a/lib/log4js.js
+++ b/lib/log4js.js
@@ -103,13 +103,15 @@ function shutdown(cb) {
     debug(`Appender shutdowns complete: ${completed} / ${shutdownFunctions}`);
     if (completed >= shutdownFunctions) {
       debug("All shutdown functions completed.");
-      cb(error);
+      if (cb) {
+        cb(error);
+      }
     }
   }
 
   if (shutdownFunctions === 0) {
     debug("No appenders with shutdown functions found.");
-    return cb();
+    return cb !== undefined && cb();
   }
 
   appendersToCheck.filter(a => a.shutdown).forEach(a => a.shutdown(complete));
diff --git a/types/test.ts b/types/test.ts
index 66c7ad3..4bb26c7 100644
--- a/types/test.ts
+++ b/types/test.ts
@@ -61,7 +61,7 @@ const logger5 = log4js.getLogger('json-test');
 logger5.info('this is just a test');
 logger5.error('of a custom appender');
 logger5.warn('that outputs json');
-log4js.shutdown(() => { });
+log4js.shutdown();
 
 log4js.configure({
 	appenders: {