diff -ur src.o/sys/kern/kern_mib.c src/sys/kern/kern_mib.c
--- src.o/sys/kern/kern_mib.c	Sat May 12 21:38:18 2007
+++ src/sys/kern/kern_mib.c	Mon May 14 00:24:25 2007
@@ -39,6 +39,7 @@
 __FBSDID("$FreeBSD: src/sys/kern/kern_mib.c,v 1.78 2007/05/12 19:38:18 wkoszek Exp $");
 
 #include "opt_posix.h"
+#include "opt_config.h"
 
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -296,8 +297,12 @@
     CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, sysctl_kern_securelvl,
     "I", "Current secure level");
 
+#ifdef INCLUDE_CONFIG_FILE
 /* Actual kernel configuration options. */
 extern char kernconfstring[];
+#else
+char kernconfstring[] = "\0";
+#endif
 
 static int
 sysctl_kern_config(SYSCTL_HANDLER_ARGS)
diff -ur src.o/usr.sbin/config/kernconf.tmpl src/usr.sbin/config/kernconf.tmpl
--- src.o/usr.sbin/config/kernconf.tmpl	Sat May 12 21:38:18 2007
+++ src/usr.sbin/config/kernconf.tmpl	Mon May 14 00:34:03 2007
@@ -7,11 +7,11 @@
 #include "opt_config.h"
 #ifdef INCLUDE_CONFIG_FILE
 
+/*
+ * For !INCLUDE_CONFIG_FILE case, you should look at kern_mib.c. This is
+ * where kernconfstring is defined then.
+ */
 const char kernconfstring[] __attribute__ ((section("kern_conf"))) =
 "%%KERNCONFFILE%%";
-
-#else
-
-const char kernconfstring[] = "\0";
 
 #endif /* INCLUDE_CONFIG_FILE */