diff --git a/lib/cpp/src/thrift/protocol/TCompactProtocol.tcc b/lib/cpp/src/thrift/protocol/TCompactProtocol.tcc
index 55b784f..79f1b6b 100644
--- a/lib/cpp/src/thrift/protocol/TCompactProtocol.tcc
+++ b/lib/cpp/src/thrift/protocol/TCompactProtocol.tcc
@@ -801,7 +801,7 @@
     case detail::compact::CT_STRUCT:
       return T_STRUCT;
     default:
-      throw TException("don't know what type: " + type);
+      throw TException(std::string("don't know what type: ") + (char)type);
   }
   return T_STOP;
 }