diff --git a/sys/kern/subr_unit.c b/sys/kern/subr_unit.c
--- a/sys/kern/subr_unit.c
+++ b/sys/kern/subr_unit.c
@@ -347,6 +347,8 @@
 	uh->high = high;
 	uh->first = 0;
 	uh->last = 1 + (high - low);
+	uh->busy = 0;
+	uh->alloc = 0;
 	check_unrhdr(uh, __LINE__);
 }