diff --git a/include/vulkan/vulkan_metal.h b/include/vulkan/vulkan_metal.h
index e6f7bf7..c6bccf5 100644
--- a/include/vulkan/vulkan_metal.h
+++ b/include/vulkan/vulkan_metal.h
@@ -52,28 +52,28 @@ VKAPI_ATTR VkResult VKAPI_CALL vkCreateMetalSurfaceEXT(
 #define VK_EXT_metal_objects 1
 #ifdef __OBJC__
 @protocol MTLDevice;
-typedef id<MTLDevice> MTLDevice_id;
+typedef __unsafe_unretained id<MTLDevice> MTLDevice_id;
 #else
 typedef void* MTLDevice_id;
 #endif
 
 #ifdef __OBJC__
 @protocol MTLCommandQueue;
-typedef id<MTLCommandQueue> MTLCommandQueue_id;
+typedef __unsafe_unretained id<MTLCommandQueue> MTLCommandQueue_id;
 #else
 typedef void* MTLCommandQueue_id;
 #endif
 
 #ifdef __OBJC__
 @protocol MTLBuffer;
-typedef id<MTLBuffer> MTLBuffer_id;
+typedef __unsafe_unretained id<MTLBuffer> MTLBuffer_id;
 #else
 typedef void* MTLBuffer_id;
 #endif
 
 #ifdef __OBJC__
 @protocol MTLTexture;
-typedef id<MTLTexture> MTLTexture_id;
+typedef __unsafe_unretained id<MTLTexture> MTLTexture_id;
 #else
 typedef void* MTLTexture_id;
 #endif
@@ -81,7 +81,7 @@ typedef void* MTLTexture_id;
 typedef struct __IOSurface* IOSurfaceRef;
 #ifdef __OBJC__
 @protocol MTLSharedEvent;
-typedef id<MTLSharedEvent> MTLSharedEvent_id;
+typedef __unsafe_unretained id<MTLSharedEvent> MTLSharedEvent_id;
 #else
 typedef void* MTLSharedEvent_id;
 #endif