diff --git a/src/System.Management.Automation/engine/remoting/client/Job.cs b/src/System.Management.Automation/engine/remoting/client/Job.cs
index b547d1f3c..8e876902c 100644
--- a/src/System.Management.Automation/engine/remoting/client/Job.cs
+++ b/src/System.Management.Automation/engine/remoting/client/Job.cs
@@ -4520,9 +4520,10 @@ namespace System.Management.Automation
         }
     }
 
+#nullable enable
     internal interface IOutputProcessingState
     {
-        event EventHandler<OutputProcessingStateEventArgs> OutputProcessingStateChanged;
+        event EventHandler<OutputProcessingStateEventArgs>? OutputProcessingStateChanged;
     }
 
     #endregion