diff --git a/shadowsocks-csharp/Controller/Service/UpdateChecker.cs b/shadowsocks-csharp/Controller/Service/UpdateChecker.cs
index 0955b255..643c7014 100644
--- a/shadowsocks-csharp/Controller/Service/UpdateChecker.cs
+++ b/shadowsocks-csharp/Controller/Service/UpdateChecker.cs
@@ -141,7 +141,7 @@ namespace Shadowsocks.Controller
             asserts.Sort(new VersionComparer());
         }
 
-        class Asset
+        public class Asset
         {
             public bool prerelease;
             public string name;
diff --git a/test/UnitTest.cs b/test/UnitTest.cs
index bb95fa50..6003770e 100755
--- a/test/UnitTest.cs
+++ b/test/UnitTest.cs
@@ -13,13 +13,13 @@ namespace test
         [TestMethod]
         public void TestCompareVersion()
         {
-            Assert.IsTrue(UpdateChecker.CompareVersion("2.3.1.0", "2.3.1") == 0);
-            Assert.IsTrue(UpdateChecker.CompareVersion("1.2", "1.3") < 0);
-            Assert.IsTrue(UpdateChecker.CompareVersion("1.3", "1.2") > 0);
-            Assert.IsTrue(UpdateChecker.CompareVersion("1.3", "1.3") == 0);
-            Assert.IsTrue(UpdateChecker.CompareVersion("1.2.1", "1.2") > 0);
-            Assert.IsTrue(UpdateChecker.CompareVersion("2.3.1", "2.4") < 0);
-            Assert.IsTrue(UpdateChecker.CompareVersion("1.3.2", "1.3.1") > 0);
+            Assert.IsTrue(UpdateChecker.Asset.CompareVersion("2.3.1.0", "2.3.1") == 0);
+            Assert.IsTrue(UpdateChecker.Asset.CompareVersion("1.2", "1.3") < 0);
+            Assert.IsTrue(UpdateChecker.Asset.CompareVersion("1.3", "1.2") > 0);
+            Assert.IsTrue(UpdateChecker.Asset.CompareVersion("1.3", "1.3") == 0);
+            Assert.IsTrue(UpdateChecker.Asset.CompareVersion("1.2.1", "1.2") > 0);
+            Assert.IsTrue(UpdateChecker.Asset.CompareVersion("2.3.1", "2.4") < 0);
+            Assert.IsTrue(UpdateChecker.Asset.CompareVersion("1.3.2", "1.3.1") > 0);
         }
 
         private void RunEncryptionRound(IEncryptor encryptor, IEncryptor decryptor)