diff --git a/Modules/CMakeDetermineSystem.cmake b/Modules/CMakeDetermineSystem.cmake
index c7f9c32a7..20c1541ba 100644
--- a/Modules/CMakeDetermineSystem.cmake
+++ b/Modules/CMakeDetermineSystem.cmake
@@ -73,7 +73,11 @@ if(CMAKE_HOST_UNIX)
 else()
   if(CMAKE_HOST_WIN32)
     set (CMAKE_HOST_SYSTEM_NAME "Windows")
-    set (CMAKE_HOST_SYSTEM_PROCESSOR "$ENV{PROCESSOR_ARCHITECTURE}")
+    if (ENV{PROCESSOR_ARCHITEW6432})
+      set (CMAKE_HOST_SYSTEM_PROCESSOR "$ENV{PROCESSOR_ARCHITEW6432}")
+    else()
+      set (CMAKE_HOST_SYSTEM_PROCESSOR "$ENV{PROCESSOR_ARCHITECTURE}")
+    endif()
   endif()
 endif()