diff --git a/compiler/cpp/src/generate/t_generator.h b/compiler/cpp/src/generate/t_generator.h
index 0a4dace..8c156f9 100644
--- a/compiler/cpp/src/generate/t_generator.h
+++ b/compiler/cpp/src/generate/t_generator.h
@@ -67,7 +67,7 @@
 
   /**
    * check whether sub-namespace declaraction is used by generator.
-   * e.g. allow 
+   * e.g. allow
    * namespace py.twisted bar
    * to specify namespace to use when -gen py:twisted is specified.
    * Will be called with subnamespace, i.e. is_valid_namespace("twisted")
diff --git a/compiler/cpp/src/generate/t_generator_registry.h b/compiler/cpp/src/generate/t_generator_registry.h
index 98a484d..0010e94 100644
--- a/compiler/cpp/src/generate/t_generator_registry.h
+++ b/compiler/cpp/src/generate/t_generator_registry.h
@@ -74,7 +74,7 @@
     return new generator(program, parsed_options, option_string);
   }
 
-  bool is_valid_namespace(const std::string& sub_namespace){
+  virtual bool is_valid_namespace(const std::string& sub_namespace) {
     return generator::is_valid_namespace(sub_namespace);
   }
 };
diff --git a/compiler/cpp/src/parse/t_program.h b/compiler/cpp/src/parse/t_program.h
index f755643..ddf7cd1 100644
--- a/compiler/cpp/src/parse/t_program.h
+++ b/compiler/cpp/src/parse/t_program.h
@@ -178,7 +178,7 @@
       if(! it->second->is_valid_namespace(sub_namespace)) {
         throw base_language +" generator does not accept '" + sub_namespace + "' as sub-namespace!";
       }
-    } 
+    }
 
     namespaces_[language] = name_space;
   }