diff --git a/lib/browser.js b/lib/browser.js
index 03bd5eac2..66b281a9d 100644
--- a/lib/browser.js
+++ b/lib/browser.js
@@ -37,7 +37,7 @@ var Browser = function (id, fullName, /* capturedBrowsers */ collection, emitter
     self.state = DISCONNECTED
     self.disconnectsCount++
     log.warn('Disconnected (%d times)' + (reason || ''), self.disconnectsCount)
-    emitter.emit('browser_error', self, 'Disconnected' + reason)
+    emitter.emit('browser_error', self, 'Disconnected' + (reason || ''))
     collection.remove(self)
   }