--- configure.ac
+++ configure.ac
@@ -2728,7 +2728,7 @@
   *-*-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_DEFINE_UNQUOTED(SWIG_LIB_WIN_UNIX, [""], [Directory for SWIG system-independent libraries (Unix install on native Windows)])
 
 SWIG_LIB_PREINST=$ABS_SRCDIR/Lib
 AC_SUBST(SWIG_LIB_PREINST)
