diff --git a/src/phage/action/PhageAgentAction.php b/src/phage/action/PhageAgentAction.php
--- a/src/phage/action/PhageAgentAction.php
+++ b/src/phage/action/PhageAgentAction.php
@@ -135,6 +135,10 @@
           throw new Exception(pht('Channel closed unexpectedly!'));
         }
       }
+
+      if ($message === null) {
+        break;
+      }
     }
   }