diff --git a/lib/travis/api/app/middleware/user_agent_tracker.rb b/lib/travis/api/app/middleware/user_agent_tracker.rb
index d7d582fa..c758e0f4 100644
--- a/lib/travis/api/app/middleware/user_agent_tracker.rb
+++ b/lib/travis/api/app/middleware/user_agent_tracker.rb
@@ -37,7 +37,7 @@ class Travis::Api::App
       end
 
       def mark_travis(agent)
-        command = agent.application.comment.detect { |c| c.start_with? "command " }
+        command = agent.application.comment.detect { |c| c.start_with? "command " } if agent.application.comment
 
         if command
           mark(:cli, :version, agent.version)