diff --git a/include/loki/Threads.h b/include/loki/Threads.h
index 97ef97b..c3e6dcb 100644
--- a/include/loki/Threads.h
+++ b/include/loki/Threads.h
@@ -62,7 +62,7 @@ namespace Loki
         { lval = val; }
     };
     
-#if defined(_WINDOWS_) && defined(_WINDOWS_H) // && defined(__WIN32)
+#if defined(_WINDOWS_) || defined(_WINDOWS_H) // && defined(__WIN32)
 
 ////////////////////////////////////////////////////////////////////////////////
 // class template ObjectLevelLockable
diff --git a/tools/RegressionTest/SingletonTest.h b/tools/RegressionTest/SingletonTest.h
index 8d368e8..dd6b6ad 100644
--- a/tools/RegressionTest/SingletonTest.h
+++ b/tools/RegressionTest/SingletonTest.h
@@ -77,7 +77,7 @@ namespace
   typedef SingletonHolder<MyClass<20>, CreateStatic, NoDestroy, SingleThreaded> t20;
 
 //#if defined(_MSC_VER) && !defined(__INTEL_COMPILER) && !defined(__MWERKS__)
-#if defined(_WINDOWS_) && defined(_WINDOWS_H) // && defined(__WIN32)
+#if defined(_WINDOWS_) || defined(_WINDOWS_H) // && defined(__WIN32)
 
   typedef SingletonHolder<MyClass<5>, CreateUsingNew, DefaultLifetime, ClassLevelLockable> t5;
   typedef SingletonHolder<MyClass<6>, CreateUsingNew, PhoenixSingleton, ClassLevelLockable> t6;
@@ -128,7 +128,7 @@ public:
     MAKE_TEST(t20)
 
 //#if defined(_MSC_VER) && !defined(__INTEL_COMPILER) && !defined(__MWERKS__)
-#if defined(_WINDOWS_) && defined(_WINDOWS_H) // && defined(__WIN32)
+#if defined(_WINDOWS_) || defined(_WINDOWS_H) // && defined(__WIN32)
 
     MAKE_TEST(t5)
     MAKE_TEST(t6)