Index: sys/kern/subr_unit.c
===================================================================
--- sys/kern/subr_unit.c
+++ sys/kern/subr_unit.c
@@ -385,6 +385,10 @@
 	TAILQ_INIT(&uh->head);
 	uh->busy = 0;
 	uh->alloc = 0;
+	uh->first = 0;
+	uh->last = 1 + (uh->high - uh->low);
+
+	check_unrhdr(uh, __LINE__);
 }
 
 static __inline int