diff --git a/src/JT808.Protocol.Test/MessageBody/JT808_0x8900Test.cs b/src/JT808.Protocol.Test/MessageBody/JT808_0x8900Test.cs
index c2df660..19ebbef 100644
--- a/src/JT808.Protocol.Test/MessageBody/JT808_0x8900Test.cs
+++ b/src/JT808.Protocol.Test/MessageBody/JT808_0x8900Test.cs
@@ -1,9 +1,8 @@
-using JT808.Protocol.Extensions;
-using JT808.Protocol.Interfaces;
+using System.Reflection;
+using JT808.Protocol.Extensions;
 using JT808.Protocol.Internal;
 using JT808.Protocol.MessageBody;
 using JT808.Protocol.Test.MessageBody.JT808_0X8900_BodiesImpl;
-using System.Reflection;
 using Xunit;
 
 namespace JT808.Protocol.Test.MessageBody
@@ -51,5 +50,31 @@ namespace JT808.Protocol.Test.MessageBody
             byte[] bytes = "0B0000303901".ToHexBytes();
             string json = JT808Serializer.Analyze<JT808_0x8900>(bytes);
         }
+
+        [Fact]
+        public void Test4()
+        {
+            var config = new DefaultGlobalConfig(GetType().Name+nameof(Test4));
+            config.JT808_0x8900_Custom_Factory.Register(Assembly.GetExecutingAssembly());
+            var serializer = config.GetSerializer();
+            var jT808_0X8900 = new JT808_0x8900
+            {
+                PassthroughType = 0x0B,
+                JT808_0X8900_BodyBase = new JT808_0X8900_Test_BodiesImpl
+                {
+                    Id = 12345,
+                    Sex = 0x01
+                }
+            };
+            string hex = serializer.Serialize(jT808_0X8900).ToHexString();
+            Assert.Equal("0B0000303901", hex);
+            byte[] bytes = hex.ToHexBytes();
+
+            jT808_0X8900 = serializer.Deserialize<JT808_0x8900>(bytes);
+            JT808_0X8900_Test_BodiesImpl jT808_0X8900_Test_BodiesImpl = (JT808_0X8900_Test_BodiesImpl)jT808_0X8900.JT808_0X8900_BodyBase;
+            Assert.Equal(0x0B, jT808_0X8900.PassthroughType);
+            Assert.Equal((uint)12345, jT808_0X8900_Test_BodiesImpl.Id);
+            Assert.Equal(0x01, jT808_0X8900_Test_BodiesImpl.Sex);
+        }
     }
 }
diff --git a/src/JT808.Protocol/Internal/JT808_0x8900_Custom_Factory.cs b/src/JT808.Protocol/Internal/JT808_0x8900_Custom_Factory.cs
index 5ac0429..c75f96b 100644
--- a/src/JT808.Protocol/Internal/JT808_0x8900_Custom_Factory.cs
+++ b/src/JT808.Protocol/Internal/JT808_0x8900_Custom_Factory.cs
@@ -15,7 +15,8 @@ namespace JT808.Protocol.Internal
 
         public void Register(Assembly externalAssembly)
         {
-            foreach (var item in externalAssembly.GetTypes().Where(x => x is JT808_0x8900_BodyBase && x.GetConstructor(Type.EmptyTypes) != default))
+            var baseType = typeof(JT808_0x8900_BodyBase);
+            foreach (var item in externalAssembly.GetTypes().Where(x => baseType.IsAssignableFrom(x) && x.GetConstructor(Type.EmptyTypes) != default))
             {
                 Register(item);
             }