diff --git a/QuickLook.Native/QuickLook.Native64/QuickLook.Native64.vcxproj b/QuickLook.Native/QuickLook.Native64/QuickLook.Native64.vcxproj
index efe59d5..f65c9c0 100644
--- a/QuickLook.Native/QuickLook.Native64/QuickLook.Native64.vcxproj
+++ b/QuickLook.Native/QuickLook.Native64/QuickLook.Native64.vcxproj
@@ -88,6 +88,7 @@
       <IntrinsicFunctions>true</IntrinsicFunctions>
       <SDLCheck>true</SDLCheck>
       <RuntimeLibrary>MultiThreaded</RuntimeLibrary>
+      <PreprocessorDefinitions>WIN64;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ClCompile>
     <Link>
       <EnableCOMDATFolding>true</EnableCOMDATFolding>