diff --git a/ConfigureChecks.cmake b/ConfigureChecks.cmake
index edd1845a..f89f70d1 100644
--- a/ConfigureChecks.cmake
+++ b/ConfigureChecks.cmake
@@ -105,5 +105,5 @@ check_cxx_source_compiles("
 
 # Detect WinRT mode
 if(CMAKE_SYSTEM_NAME STREQUAL "WindowsStore")
-	set(PLATFORM WINRT 1)
+  set(PLATFORM_WINRT 1)
 endif()