diff --git a/Utilities/cmcurl/CMakeLists.txt b/Utilities/cmcurl/CMakeLists.txt
index e2c64db5f5..2a8a616ca6 100644
--- a/Utilities/cmcurl/CMakeLists.txt
+++ b/Utilities/cmcurl/CMakeLists.txt
@@ -246,6 +246,12 @@ MACRO(CHECK_INCLUDE_FILE_CONCAT FILE VARIABLE)
 ENDMACRO(CHECK_INCLUDE_FILE_CONCAT)
 
 # Check for header files
+IF(UNIX)
+  SET(HAVE_WINDOWS_H 0)
+  SET(HAVE_WINSOCK_H 0)
+  SET(HAVE_WS2TCPIP_H 0)
+  SET(HAVE_WINSOCK2_H 0)
+ENDIF(UNIX)
 IF(NOT UNIX)
   CHECK_INCLUDE_FILE_CONCAT("ws2tcpip.h"     HAVE_WS2TCPIP_H)
   CHECK_INCLUDE_FILE_CONCAT("winsock2.h"     HAVE_WINSOCK2_H)