diff --git a/tests/strings/iostream.cpp b/tests/strings/iostream.cpp
index 6e40cbb28f..0abf396211 100644
--- a/tests/strings/iostream.cpp
+++ b/tests/strings/iostream.cpp
@@ -54,8 +54,10 @@ void StringIostreamTestCase::Out()
     s << wxString("hello");
     ASSERT_OSTREAM_EQUAL("hello", s);
 
+#ifndef __MINGW32__
     std::wostringstream ws;
     ws << wxString("bye");
     ASSERT_WOSTREAM_EQUAL(L"bye", ws);
+#endif
 }
 
diff --git a/tests/strings/vsnprintf.cpp b/tests/strings/vsnprintf.cpp
index bef2356214..61b9abae3f 100644
--- a/tests/strings/vsnprintf.cpp
+++ b/tests/strings/vsnprintf.cpp
@@ -376,7 +376,7 @@ void VsnprintfTestCase::LongLong()
 
 #ifdef __WXMSW__
     CMP3("123456789", "%I64d", (wxLongLong_t)123456789);
-    CMP3("123456789abcdef", "%I64x", (wxLongLong_t)0x123456789abcdef);
+    CMP3("123456789abcdef", "%I64x", wxLL(0x123456789abcdef));
 #endif
 }
 #endif