diff --git a/CMakeLists.txt b/CMakeLists.txt
index 03db8f5..9af43d3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -84,6 +84,7 @@ elseif(APPLE)
   find_library(OPENGL_LIBRARY OpenGL)
   if (NOT CMAKE_OSX_DEPLOYMENT_TARGET OR CMAKE_OSX_DEPLOYMENT_TARGET VERSION_GREATER 10.10)
     find_library(METAL_LIBRARY Metal)
+    list(APPEND _BOO_SYS_DEFINES -DBOO_HAS_METAL=1)
   else()
     set(METAL_LIBRARY "")
   endif()
diff --git a/include/boo/System.hpp b/include/boo/System.hpp
index 1592744..4ca25a1 100644
--- a/include/boo/System.hpp
+++ b/include/boo/System.hpp
@@ -5,29 +5,29 @@
 
 #ifndef ENABLE_BITWISE_ENUM
 #define ENABLE_BITWISE_ENUM(type)\
-inline type operator|(type a, type b)\
+constexpr type operator|(type a, type b)\
 {\
     using T = std::underlying_type_t<type>;\
     return type(static_cast<T>(a) | static_cast<T>(b));\
 }\
-inline type operator&(type a, type b)\
+constexpr type operator&(type a, type b)\
 {\
     using T = std::underlying_type_t<type>;\
     return type(static_cast<T>(a) & static_cast<T>(b));\
 }\
-inline type& operator|=(type& a, const type& b)\
+constexpr type& operator|=(type& a, const type& b)\
 {\
     using T = std::underlying_type_t<type>;\
     a = type(static_cast<T>(a) | static_cast<T>(b));\
     return a;\
 }\
-inline type& operator&=(type& a, const type& b)\
+constexpr type& operator&=(type& a, const type& b)\
 {\
     using T = std::underlying_type_t<type>;\
     a = type(static_cast<T>(a) & static_cast<T>(b));\
     return a;\
 }\
-inline type operator~(const type& key)\
+constexpr type operator~(const type& key)\
 {\
     using T = std::underlying_type_t<type>;\
     return type(~static_cast<T>(key));\
diff --git a/include/boo/graphicsdev/Metal.hpp b/include/boo/graphicsdev/Metal.hpp
index 60a6fb0..1ea7851 100644
--- a/include/boo/graphicsdev/Metal.hpp
+++ b/include/boo/graphicsdev/Metal.hpp
@@ -1,11 +1,7 @@
 #ifndef GDEV_METAL_HPP
 #define GDEV_METAL_HPP
 #ifdef __APPLE__
-
-#include <Availability.h>
-
-#if __MAC_OS_X_VERSION_MAX_ALLOWED >= 101100
-#define BOO_HAS_METAL 1
+#if BOO_HAS_METAL
 
 #include "IGraphicsDataFactory.hpp"
 #include "IGraphicsCommandQueue.hpp"
@@ -80,9 +76,6 @@ public:
 
 }
 
-#else
-#define BOO_HAS_METAL 0
 #endif
-
 #endif // __APPLE__
 #endif // GDEV_METAL_HPP
diff --git a/lib/graphicsdev/Metal.mm b/lib/graphicsdev/Metal.mm
index 7ea1e62..e93aa3d 100644
--- a/lib/graphicsdev/Metal.mm
+++ b/lib/graphicsdev/Metal.mm
@@ -621,10 +621,6 @@ struct MetalShaderDataBinding : IShaderDataBinding
         }
         for (size_t i=0 ; i<texCount ; ++i)
         {
-#ifndef NDEBUG
-            if (!texs[i])
-                Log.report(logvisor::Fatal, "null texture %d provided to newShaderDataBinding", int(i));
-#endif
             m_texs[i] = texs[i];
         }
     }
@@ -653,7 +649,8 @@ struct MetalShaderDataBinding : IShaderDataBinding
                     [enc setVertexBuffer:GetBufferGPUResource(m_ubufs[i], b) offset:0 atIndex:i+2];
             }
         for (size_t i=0 ; i<m_texCount ; ++i)
-            [enc setFragmentTexture:GetTextureGPUResource(m_texs[i], b) atIndex:i];
+            if (m_texs[i])
+                [enc setFragmentTexture:GetTextureGPUResource(m_texs[i], b) atIndex:i];
     }
 };
 
diff --git a/lib/mac/CocoaCommon.hpp b/lib/mac/CocoaCommon.hpp
index d748ee0..9a0beaa 100644
--- a/lib/mac/CocoaCommon.hpp
+++ b/lib/mac/CocoaCommon.hpp
@@ -6,10 +6,7 @@
 #error ARC Required
 #endif
 
-#include <Availability.h>
-
-#if __MAC_OS_X_VERSION_MAX_ALLOWED >= 101100
-#define BOO_HAS_METAL 1
+#if BOO_HAS_METAL
 
 #include <Metal/Metal.h>
 #include <QuartzCore/CAMetalLayer.h>
@@ -35,7 +32,6 @@ struct MetalContext
 }
 
 #else
-#define BOO_HAS_METAL 0
 namespace boo
 {
     struct MetalContext {};