Use NULL in preference to 0 for pointers.

sys/kern/subr_firmware.c

@@ -525,7 +525,7 @@ firmware_modevent(module_t mod, int type, void *unused)
 static moduledata_t firmware_mod = {
 	"firmware",
 	firmware_modevent,
-	0
+	NULL
 };
 DECLARE_MODULE(firmware, firmware_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST);
 MODULE_VERSION(firmware, 1);

sys/kern/subr_prf.c

@@ -959,7 +959,7 @@ sysctl_kern_msgbuf(SYSCTL_HANDLER_ARGS)
 }
 
 SYSCTL_PROC(_kern, OID_AUTO, msgbuf, CTLTYPE_STRING | CTLFLAG_RD,
-    0, 0, sysctl_kern_msgbuf, "A", "Contents of kernel message buffer");
+    NULL, 0, sysctl_kern_msgbuf, "A", "Contents of kernel message buffer");
 
 static int msgbuf_clearflag;