diff --git a/Content.IntegrationTests/Tests/Networking/SimplePredictReconcileTest.cs b/Content.IntegrationTests/Tests/Networking/SimplePredictReconcileTest.cs
index ec60af5d4232..52d464fa41ed 100644
--- a/Content.IntegrationTests/Tests/Networking/SimplePredictReconcileTest.cs
+++ b/Content.IntegrationTests/Tests/Networking/SimplePredictReconcileTest.cs
@@ -10,6 +10,7 @@
 using Robust.Shared.GameStates;
 using Robust.Shared.IoC;
 using Robust.Shared.Map;
+using Robust.Shared.Serialization;
 using Robust.Shared.Timing;
 
 namespace Content.IntegrationTests.Tests.Networking
@@ -420,6 +421,7 @@ private void HandleMessage(SetFooMessage message, EntitySessionEventArgs args)
             }
         }
 
+        [Serializable, NetSerializable]
         public sealed class SetFooMessage : EntityEventArgs
         {
             public SetFooMessage(NetEntity uid, bool newFoo)