diff --git a/config.h.in b/config.h.in
index 254e1f334..e8107f685 100644
--- a/config.h.in
+++ b/config.h.in
@@ -113,3 +113,6 @@
 
 /* Define if you have the <termios.h> header file.  */
 #undef HAVE_TERMIOS_H
+
+/* Define if you have the -lshadow library.  */
+#undef HAVE_LIBSHADOW