diff --git a/lib/csharp/src/Protocol/TProtocolUtil.cs b/lib/csharp/src/Protocol/TProtocolUtil.cs
index 0932a7f..0606c71 100644
--- a/lib/csharp/src/Protocol/TProtocolUtil.cs
+++ b/lib/csharp/src/Protocol/TProtocolUtil.cs
@@ -95,6 +95,8 @@
                         }
                         prot.ReadListEnd();
                         break;
+                    default:
+                        throw new TProtocolException(TProtocolException.INVALID_DATA, "Unknown data type " + type.ToString("d"));
                 }
 
             }