diff --git a/Core/FileSystems/DirectoryFileSystem.h b/Core/FileSystems/DirectoryFileSystem.h
index 6b87c3f784..c187db572c 100644
--- a/Core/FileSystems/DirectoryFileSystem.h
+++ b/Core/FileSystems/DirectoryFileSystem.h
@@ -28,6 +28,26 @@
 typedef void * HANDLE;
 #endif
 
+#if defined(__APPLE__)
+
+#if TARGET_OS_IPHONE
+#define HOST_IS_CASE_SENSITIVE true
+#elif TARGET_IPHONE_SIMULATOR
+#define HOST_IS_CASE_SENSITIVE false
+#else
+// Mac OSX case sensitivity defaults off, but is user configurable (when
+// creating a filesytem), so assume the worst:
+#define HOST_IS_CASE_SENSITIVE true
+#endif
+
+#elif defined(_WIN32) || defined(__SYMBIAN32__)
+#define HOST_IS_CASE_SENSITIVE false
+
+#else  // Android, Linux, BSD (and the rest?)
+#define HOST_IS_CASE_SENSITIVE true
+
+#endif
+
 class DirectoryFileSystem : public IFileSystem {
 public:
 	DirectoryFileSystem(IHandleAllocator *_hAlloc, std::string _basePath);