diff --git a/tests/regex/wxregextest.cpp b/tests/regex/wxregextest.cpp
index 7d7b3085b9..39d61a1dda 100644
--- a/tests/regex/wxregextest.cpp
+++ b/tests/regex/wxregextest.cpp
@@ -169,7 +169,7 @@ void RegExReplaceTestCase::runTest()
     msgstr.Printf(_T("returns '%s' (expected '%s')"), text.c_str(), m_expected.c_str());
     CPPUNIT_ASSERT_MESSAGE((const char*)msgstr.mb_str(), text == m_expected);
 
-    msgstr.Printf(_T("matches %d times (expected %d)"), nRepl, m_count);
+    msgstr << _T("matches ") << nRepl << _T(" times (expected ") << m_count << _T(")");
     CPPUNIT_ASSERT_MESSAGE((const char*)msgstr.mb_str(), nRepl == m_count);
 }