diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2786e35884..532ea09beb 100755
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -360,11 +360,13 @@ elseif(EMSCRIPTEN)
 elseif (APPLE AND NOT OGRE_BUILD_PLATFORM_APPLE_IOS)
 
   set(XCODE_ATTRIBUTE_SDKROOT macosx)
-  if(CMAKE_GENERATOR STREQUAL "Unix Makefiles")
-    execute_process(COMMAND xcodebuild -version -sdk "${XCODE_ATTRIBUTE_SDKROOT}" Path | head -n 1 OUTPUT_VARIABLE CMAKE_OSX_SYSROOT)
-    string(REGEX REPLACE "(\r?\n)+$" "" CMAKE_OSX_SYSROOT "${CMAKE_OSX_SYSROOT}")
-  else()
-    set(CMAKE_OSX_SYSROOT macosx)
+  if(NOT CMAKE_OSX_SYSROOT)
+    if(CMAKE_GENERATOR STREQUAL "Unix Makefiles")
+      execute_process(COMMAND xcodebuild -version -sdk "${XCODE_ATTRIBUTE_SDKROOT}" Path | head -n 1 OUTPUT_VARIABLE CMAKE_OSX_SYSROOT)
+      string(REGEX REPLACE "(\r?\n)+$" "" CMAKE_OSX_SYSROOT "${CMAKE_OSX_SYSROOT}")
+    else()
+      set(CMAKE_OSX_SYSROOT macosx)
+    endif()
   endif()
 
   set( CMAKE_XCODE_ATTRIBUTE_CLANG_ENABLE_OBJC_ARC YES )