diff --git a/Utilities/cmcurl/CMakeLists.txt b/Utilities/cmcurl/CMakeLists.txt
index 5cef59f3a0..6a34e8dd55 100644
--- a/Utilities/cmcurl/CMakeLists.txt
+++ b/Utilities/cmcurl/CMakeLists.txt
@@ -316,7 +316,7 @@ include (CheckCSourceCompiles)
 
 # 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)