diff --git a/src/TamerLib/Abstracts/ExitCodes/WorkerExitCodes.php b/src/TamerLib/Abstracts/ExitCodes/WorkerExitCodes.php
index 4eb701b..4dd99f6 100644
--- a/src/TamerLib/Abstracts/ExitCodes/WorkerExitCodes.php
+++ b/src/TamerLib/Abstracts/ExitCodes/WorkerExitCodes.php
@@ -2,7 +2,7 @@
 
     namespace TamerLib\Abstracts\ExitCodes;
 
-    class WorkerExitCodes
+    abstract class WorkerExitCodes
     {
         const GracefulShutdown = 0;