--- xnu/xnu-344.2/bsd/miscfs/devfs/devfs_tree.c
+++ xnu/xnu-201/bsd/miscfs/devfs/devfs_tree.c
@@ -1051,6 +1051,8 @@
 	return error;
 }
 
+#include <sys/subr_prf.h>
+
 /*
  * Function: devfs_make_node
  *
@@ -1075,6 +1077,7 @@
 	devnode_type_t	typeinfo;
 
 	char *name, *path, buf[256]; /* XXX */
+	char * b_ptr = buf;
 	boolean_t   funnel_state;
 	int i;
 	va_list ap;
@@ -1090,8 +1093,9 @@
 		goto out;
 
 	va_start(ap, fmt);
-	vsnprintf(buf, sizeof(buf), fmt, ap);
+	prf(fmt, ap, TOSTR, (struct tty *)&b_ptr);
 	va_end(ap);
+	*b_ptr = 0;
 
 	name = NULL;
 
@@ -1148,6 +1152,7 @@
 
 	va_list ap;
 	char *p, buf[256]; /* XXX */
+	char * b_ptr = buf;
 	int i;
 	boolean_t   funnel_state;
 
@@ -1159,8 +1164,9 @@
 	}
 
 	va_start(ap, fmt);
-	vsnprintf(buf, sizeof(buf), fmt, ap);
+	prf(fmt, ap, TOSTR, (struct tty *)&b_ptr);
 	va_end(ap);
+	*b_ptr = 0;
 
 	p = NULL;