diff --git a/include/wx/cppunit.h b/include/wx/cppunit.h
index b7848534a3..8bbc99f7f5 100644
--- a/include/wx/cppunit.h
+++ b/include/wx/cppunit.h
@@ -78,6 +78,16 @@
     WXTEST_ANY_WITH_CONDITION(suiteName, Condition, testMethod, CPPUNIT_TEST_FAIL(testMethod))
 
 
+///////////////////////////////////////////////////////////////////////////////
+// stream inserter for wxString
+//
+
+inline std::ostream& operator<<(std::ostream& o, const wxString& s)
+{
+    return o << s.mb_str();
+}
+
+
 ///////////////////////////////////////////////////////////////////////////////
 // Some more compiler warning tweaking and auto linking.
 //