diff --git a/framework/src/Volo.Abp.ObjectExtending/Volo/Abp/Data/ExtraPropertyDictionary.cs b/framework/src/Volo.Abp.ObjectExtending/Volo/Abp/Data/ExtraPropertyDictionary.cs
new file mode 100644
index 0000000000..86a43d77a3
--- /dev/null
+++ b/framework/src/Volo.Abp.ObjectExtending/Volo/Abp/Data/ExtraPropertyDictionary.cs
@@ -0,0 +1,19 @@
+using System;
+using System.Collections.Generic;
+
+namespace Volo.Abp.Data
+{
+    [Serializable]
+    public class ExtraPropertyDictionary : Dictionary<string, object>
+    {
+        public ExtraPropertyDictionary()
+        {
+
+        }
+
+        public ExtraPropertyDictionary(IDictionary<string, object> dictionary)
+            : base(dictionary)
+        {
+        }
+    }
+}
diff --git a/framework/src/Volo.Abp.ObjectExtending/Volo/Abp/Data/IHasExtraProperties.cs b/framework/src/Volo.Abp.ObjectExtending/Volo/Abp/Data/IHasExtraProperties.cs
index 61a9f267f0..cc236508b2 100644
--- a/framework/src/Volo.Abp.ObjectExtending/Volo/Abp/Data/IHasExtraProperties.cs
+++ b/framework/src/Volo.Abp.ObjectExtending/Volo/Abp/Data/IHasExtraProperties.cs
@@ -1,6 +1,4 @@
-using System.Collections.Generic;
-
-namespace Volo.Abp.Data
+namespace Volo.Abp.Data
 {
     //TODO: Move to Volo.Abp.Data.ObjectExtending namespace at 4.0?
 
@@ -8,16 +6,4 @@ namespace Volo.Abp.Data
     {
         ExtraPropertyDictionary ExtraProperties { get; }
     }
-
-    public class ExtraPropertyDictionary : Dictionary<string, object>
-    {
-        public ExtraPropertyDictionary()
-        {
-        }
-
-        public ExtraPropertyDictionary(IDictionary<string, object> dictionary)
-            : base(dictionary)
-        {
-        }
-    }
 }