diff --git a/configure.in b/configure.in
index 153bb07b..b430afbd 100644
--- a/configure.in
+++ b/configure.in
@@ -83,9 +83,9 @@ AC_SEARCH_LIBS(getipnodebyname, nsl,
 dnl Checks for header files.
 AC_HEADER_STDC
 
-AC_CHECK_HEADER(stdint.h, AC_DEFINE(HAVE_STDINT_H, 1),,)
-AC_CHECK_HEADER(pwd.h, AC_DEFINE(CHUID, 1),,)
-AC_CHECK_HEADER(unistd.h, AC_DEFINE(CHROOT, 1),,)
+AC_CHECK_HEADER(stdint.h, AC_DEFINE(HAVE_STDINT_H, 1, [Define if you have stdint.h]),,)
+AC_CHECK_HEADER(pwd.h, AC_DEFINE(CHUID, 1, [Define if you have pwd.h]),,)
+AC_CHECK_HEADER(unistd.h, AC_DEFINE(CHROOT, 1, [Define if you have unistd.h]),,)
 
 dnl Checks for typedefs, structures, and compiler characteristics.
 AC_C_CONST