diff --git a/configure.in b/configure.in
index 910845728..3dc7139f2 100644
--- a/configure.in
+++ b/configure.in
@@ -1924,6 +1924,15 @@ AC_ARG_WITH(swiglibdir,[  --with-swiglibdir=DIR   Put SWIG system-independent li
 AC_SUBST(swig_lib)
 AC_DEFINE_DIR(SWIG_LIB, swig_lib, [Directory for SWIG system-independent libraries])
 
+case $host in
+        # Windows does not understand unix directories. Convert into a windows directory with drive letter.
+        *-*-mingw*) SWIG_LIB_WIN_UNIX=`cmd //c echo $SWIG_LIB | sed -e "s/[ ]*$//"`;; # This echo converts unix to mixed paths. Then zap unexpected trailing space.
+        *-*-cygwin*) SWIG_LIB_WIN_UNIX=`cygpath --mixed "$SWIG_LIB"`;;
+        *) SWIG_LIB_WIN_UNIX="";;
+esac
+AC_DEFINE_UNQUOTED(SWIG_LIB_WIN_UNIX, ["$SWIG_LIB_WIN_UNIX"], [Directory for SWIG system-independent libraries (Unix install on native Windows)])
+
+
 AC_CONFIG_FILES([			        \
     Makefile				        \
     swig.spec				        \