diff --git a/CMakeLists.txt b/CMakeLists.txt
index bee47972c..87f1c746a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -327,7 +327,7 @@ if(UNIX)
   endif()
 elseif(WIN32)
   set(CPACK_GENERATOR NSIS ${CPACK_GENERATOR})
-  if("${CMAKE_GENERATOR_PLATFORM}" MATCHES "(x64)")
+  if(CMAKE_SIZEOF_VOID_P EQUAL 8)
     set(TRICE_IS_64_BIT 1)
   else()
     set(TRICE_IS_64_BIT 0)