diff --git a/sys/vm/vm_phys.c b/sys/vm/vm_phys.c
--- a/sys/vm/vm_phys.c
+++ b/sys/vm/vm_phys.c
@@ -1780,12 +1780,10 @@
 {
 	int i;
 
-	for (i = 0; phys_avail[i + 1]; i += 2)
-		continue;
-	if (i > PHYS_AVAIL_ENTRIES)
-		panic("Improperly terminated phys_avail %d entries", i);
-
-	return (i);
+	for (i = 0; i < PHYS_AVAIL_COUNT; i += 2)
+		if (phys_avail[i] == 0 && phys_avail[i+1] == 0)
+			return (i);
+	panic("Improperly terminated phys_avail[]");
 }
 
 /*