Index: share/man/man9/memguard.9
===================================================================
--- share/man/man9/memguard.9
+++ share/man/man9/memguard.9
@@ -176,6 +176,8 @@
 .Xr uma 9
 zones that have been initialized with the
 .Dv UMA_ZONE_NOFREE
+or
+.Dv UMA_ZONE_REFCNT
 flag set, since it can produce false positives on them.
 However, this safety measure can be turned off by setting bit 3
 of the
Index: sys/vm/memguard.c
===================================================================
--- sys/vm/memguard.c
+++ sys/vm/memguard.c
@@ -504,6 +504,9 @@
 	    zone->uz_flags & UMA_ZONE_NOFREE)
 		return (0);
 
+	if (zone->uz_flags & UMA_ZONE_REFCNT)
+		return (0);
+
 	if (memguard_cmp(zone->uz_size))
 		return (1);