diff --git a/lib/streamlogger.js b/lib/streamlogger.js
index c837af5..80f8ef4 100644
--- a/lib/streamlogger.js
+++ b/lib/streamlogger.js
@@ -121,12 +121,11 @@ StreamLogger.prototype.logAtLevel = function(message,level,callback) {
   this.emitter.emit('loggedMessage-' + levelName, message);
 
   //Check if there's a custom formatting callback
-  if (this.format)
-    var outMessage = this.format(message,levelName);
-  else
-    var outMessage = (new Date).toUTCString() + ' - ' +
-                       levelName + ': ' + message; 
-  
+  var outMessage = this.format(message, levelName);
+  if(!outMessage) {
+    outMessage = (new Date).toUTCString() + ' - ' + levelName + ': ' + message; 
+  }
+
   for (var i = this.fstreams.length; i != 0; i--) {
     var fstream = this.fstreams[i - 1];
     //Ideally we could trap the errors #write creates, I'm not sure