diff --git a/Source/JavaScriptCore/API/WebKitAvailability.h b/Source/JavaScriptCore/API/WebKitAvailability.h
index ab53183..1310dec 100644
--- a/Source/JavaScriptCore/API/WebKitAvailability.h
+++ b/Source/JavaScriptCore/API/WebKitAvailability.h
@@ -27,57 +27,12 @@
 #define __WebKitAvailability__
 
 #if defined(__APPLE__)
-
-#include <AvailabilityMacros.h>
 #include <CoreFoundation/CoreFoundation.h>
-
-#if !TARGET_OS_IPHONE && __MAC_OS_X_VERSION_MIN_REQUIRED < 101100
-/* To support availability macros that mention newer OS X versions when building on older OS X versions,
-   we provide our own definitions of the underlying macros that the availability macros expand to. We're
-   free to expand the macros as no-ops since frameworks built on older OS X versions only ship bundled with
-   an application rather than as part of the system.
-*/
-
-#ifndef __NSi_10_10 // Building from trunk rather than SDK.
-#define __NSi_10_10 introduced=10.0 // Use 10.0 to indicate that everything is available.
-#endif
-
-#ifndef __NSi_10_11 // Building from trunk rather than SDK.
-#define __NSi_10_11 introduced=10.0 // Use 10.0 to indicate that everything is available.
-#endif
-
-#ifndef __NSi_10_12 // Building from trunk rather than SDK.
-#define __NSi_10_12 introduced=10.0 // Use 10.0 to indicate that everything is available.
-#endif
-
-#ifndef __AVAILABILITY_INTERNAL__MAC_10_9
-#define __AVAILABILITY_INTERNAL__MAC_10_9
-#endif
-
-#ifndef __AVAILABILITY_INTERNAL__MAC_10_10
-#define __AVAILABILITY_INTERNAL__MAC_10_10
 #endif
 
-#ifndef AVAILABLE_MAC_OS_X_VERSION_10_9_AND_LATER
-#define AVAILABLE_MAC_OS_X_VERSION_10_9_AND_LATER
-#endif
-
-#ifndef AVAILABLE_MAC_OS_X_VERSION_10_10_AND_LATER
-#define AVAILABLE_MAC_OS_X_VERSION_10_10_AND_LATER
-#endif
-
-#endif /* __MAC_OS_X_VERSION_MIN_REQUIRED <= 101100 */
-
-#if defined(BUILDING_GTK__)
 #undef CF_AVAILABLE
 #define CF_AVAILABLE(_mac, _ios)
 #undef CF_ENUM_AVAILABLE
 #define CF_ENUM_AVAILABLE(_mac, _ios)
-#endif
-
-#else
-#define CF_AVAILABLE(_mac, _ios)
-#define CF_ENUM_AVAILABLE(_mac, _ios)
-#endif
 
 #endif /* __WebKitAvailability__ */