Fixed bug spotted by danielr
diff --git a/src/ProtocolBuffers.Test/GeneratedMessageTest.cs b/src/ProtocolBuffers.Test/GeneratedMessageTest.cs
index aee11d8..5f98817 100644
--- a/src/ProtocolBuffers.Test/GeneratedMessageTest.cs
+++ b/src/ProtocolBuffers.Test/GeneratedMessageTest.cs
@@ -452,5 +452,11 @@
       Assert.AreEqual(UnitTestProtoFile.RepeatedNestedMessageExtensionFieldNumber, 48);
       Assert.AreEqual(UnitTestProtoFile.RepeatedNestedEnumExtensionFieldNumber, 51);
     }
+
+    [Test]
+    public void EmptyPackedValue() {
+      TestPackedTypes empty = new TestPackedTypes.Builder().Build();
+      Assert.AreEqual(0, empty.SerializedSize);
+    }
   }
 }