diff --git a/lib/forever/cli.js b/lib/forever/cli.js
index bc6efc79..57e79b8c 100644
--- a/lib/forever/cli.js
+++ b/lib/forever/cli.js
@@ -277,6 +277,12 @@ cli.clear = function (key) {
 // specified then it will display log files for all running forever processes.
 //
 cli.logs = function (index) {
+  if (typeof index === 'undefined') {
+    forever.log.warn('Cannot show logs of unknown process');
+    forever.log.warn('usage: forever logs [index | script]');
+    return;
+  }
+  
   //
   // Helper function for listing all log files
   //