diff --git a/CMakeLists.txt b/CMakeLists.txt
index 31a0d41e3..14ecceba8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -251,7 +251,7 @@ include (CMakeDependentOption)
 
 # On windows preload settings
 if(WIN32)
-  set(CMAKE_REQUIRED_DEFINITIONS "${CMAKE_REQUIRED_DEFINITIONS} -D_WINSOCKAPI_")
+  set(CMAKE_REQUIRED_DEFINITIONS "${CMAKE_REQUIRED_DEFINITIONS} -D_WINSOCKAPI_=")
   include(${CMAKE_CURRENT_SOURCE_DIR}/CMake/Platforms/WindowsCache.cmake)
 endif(WIN32)