diff --git a/cmake/Config.cmake b/cmake/Config.cmake
index a1c626408..7fed4ac4a 100644
--- a/cmake/Config.cmake
+++ b/cmake/Config.cmake
@@ -6,9 +6,9 @@ if(${CMAKE_SYSTEM_NAME} MATCHES "Windows")
     # detect the architecture (note: this test won't work for cross-compilation)
     include(CheckTypeSize)
     check_type_size(void* SIZEOF_VOID_PTR)
-    if(${SIZEOF_VOID_PTR} EQUAL "4")
+    if("${SIZEOF_VOID_PTR}" STREQUAL "4")
         set(ARCH_32BITS 1)
-    elseif(${SIZEOF_VOID_PTR} EQUAL "8")
+    elseif("${SIZEOF_VOID_PTR}" STREQUAL "8")
         set(ARCH_64BITS 1)
     else()
         message(FATAL_ERROR "Unsupported architecture")