diff --git a/src/Orchard.Tests.Modules/Settings/Topology/ShellDescriptorManagerTests.cs b/src/Orchard.Tests.Modules/Settings/Topology/ShellDescriptorManagerTests.cs
index 6c41371af..931892176 100644
--- a/src/Orchard.Tests.Modules/Settings/Topology/ShellDescriptorManagerTests.cs
+++ b/src/Orchard.Tests.Modules/Settings/Topology/ShellDescriptorManagerTests.cs
@@ -25,7 +25,7 @@ namespace Orchard.Tests.Modules.Settings.Topology {
             public void Notify_Obsolete(string messageName, IDictionary<string, string> eventData) {
             }
 
-            public void Notify(string messageName, Dictionary<string, object> eventData) {                
+            public void Notify(string messageName, IDictionary<string, object> eventData) {                
                 LastMessageName = messageName;
                 LastEventData = eventData;
             }
diff --git a/src/Orchard/Events/DefaultOrchardEventBus.cs b/src/Orchard/Events/DefaultOrchardEventBus.cs
index d8eebfac4..161352584 100644
--- a/src/Orchard/Events/DefaultOrchardEventBus.cs
+++ b/src/Orchard/Events/DefaultOrchardEventBus.cs
@@ -26,7 +26,7 @@ namespace Orchard.Events {
             _handlers().Invoke(handler => handler.Process(messageName, eventData), Logger);
         }
 
-        public void Notify(string messageName, Dictionary<string, object> eventData) {
+        public void Notify(string messageName, IDictionary<string, object> eventData) {
             string[] parameters = messageName.Split('.');
             if (parameters.Length != 2) {
                 throw new ArgumentException(messageName + T(" is not formatted correctly"));
diff --git a/src/Orchard/Events/IEventBus.cs b/src/Orchard/Events/IEventBus.cs
index 46cb7f214..2f7232f90 100644
--- a/src/Orchard/Events/IEventBus.cs
+++ b/src/Orchard/Events/IEventBus.cs
@@ -3,6 +3,6 @@
 namespace Orchard.Events {
     public interface IEventBus : IDependency {
         void Notify_Obsolete(string messageName, IDictionary<string, string> eventData);
-        void Notify(string messageName, Dictionary<string, object> eventData);
+        void Notify(string messageName, IDictionary<string, object> eventData);
     }
 }