diff --git a/configure.ac b/configure.ac
index a79458301f9b..e0a72723eaeb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3967,7 +3967,8 @@ if test "$_os" = "WINNT"; then
         # Remove /cl.exe from CC case insensitive
         AC_MSG_NOTICE([found Visual C++ $vcyear])
 
-        export INCLUDE=`cygpath -d "$COMPATH/Include"`
+        main_include_dir=`cygpath -d -m "$COMPATH/Include"`
+        CPPFLAGS="$CPPFLAGS -I$main_include_dir"
 
         PathFormat "$COMPATH"
         COMPATH=`win_short_path_for_make "$formatted_path"`