diff --git a/tests/mbconv/mbconvtest.cpp b/tests/mbconv/mbconvtest.cpp
index 78e4d05932..df5216fe17 100644
--- a/tests/mbconv/mbconvtest.cpp
+++ b/tests/mbconv/mbconvtest.cpp
@@ -984,35 +984,23 @@ void MBConvTestCase::CP1252Tests()
 
 void MBConvTestCase::LibcTests()
 {
-    // There isn't a locale that all systems support (except "C"), so leave
-    // this one disabled for non-Windows systems for the moment, until
-    // a solution can be found.
-#ifdef __WXMSW__
+    // The locale name are OS-dependent so this test is done only under Windows
+    // when using MSVC (surprisingly it fails with MinGW, even though it's
+    // supposed to use the same CRT -- no idea why and unfortunately gdb is too
+    // flaky to debug it)
+#ifdef __VISUALC__
+    LocaleSetter loc("English_United States.1252");
 
-#ifdef __WXMSW__
-    setlocale( LC_ALL, "English_United States.1252" );
-    const unsigned char* systemMB = CP1252;
-    size_t systemMB_size = sizeof(CP1252);
-    const unsigned char* systemMB_utf8 = CP1252_utf8;
-    size_t systemMB_utf8_size = sizeof(CP1252_utf8);
-#else
-    setlocale( LC_ALL, "en_US.iso8859-1" );
-    const unsigned char* systemMB = iso8859_1;
-    size_t systemMB_size = sizeof(iso8859_1);
-    const unsigned char* systemMB_utf8 = iso8859_1_utf8;
-    size_t systemMB_utf8_size = sizeof(iso8859_1_utf8);
-#endif
     wxMBConvLibc convLibc;
     TestCoder(
-        (const char*)systemMB,
-        systemMB_size,
-        (const char*)systemMB_utf8,
-        systemMB_utf8_size,
+        (const char*)CP1252,
+        sizeof(CP1252),
+        (const char*)CP1252_utf8,
+        sizeof(CP1252_utf8),
         convLibc,
         1
         );
-
-#endif // __WXMSW__
+#endif // __VISUALC__
 }
 
 // verifies that the specified mb sequences decode to the specified wc sequence
diff --git a/tests/testprec.h b/tests/testprec.h
index 853a62644b..eb232b128e 100644
--- a/tests/testprec.h
+++ b/tests/testprec.h
@@ -81,15 +81,26 @@ extern void SetProcessEventFunc(ProcessEventFunc func);
 
 extern bool IsNetworkAvailable();
 
-// helper class setting the locale to "C" for its lifetime
-class CLocaleSetter
+// Helper class setting the locale to the given one for its lifetime.
+class LocaleSetter
 {
 public:
-    CLocaleSetter() : m_locOld(setlocale(LC_ALL, "C")) { }
-    ~CLocaleSetter() { setlocale(LC_ALL, m_locOld); }
+    LocaleSetter(const char *loc) : m_locOld(setlocale(LC_ALL, loc)) { }
+    ~LocaleSetter() { setlocale(LC_ALL, m_locOld); }
 
 private:
     const char * const m_locOld;
+
+    wxDECLARE_NO_COPY_CLASS(LocaleSetter);
+};
+
+// An even simpler helper for setting the locale to "C" one during its lifetime.
+class CLocaleSetter : private LocaleSetter
+{
+public:
+    CLocaleSetter() : LocaleSetter("C") { }
+
+private:
     wxDECLARE_NO_COPY_CLASS(CLocaleSetter);
 };