diff --git a/sys/net/altq/altq_rmclass.c b/sys/net/altq/altq_rmclass.c
--- a/sys/net/altq/altq_rmclass.c
+++ b/sys/net/altq/altq_rmclass.c
@@ -245,7 +245,7 @@
 	cl->flags_ = flags;
 
 #if 1 /* minidle is also scaled in ALTQ */
-	cl->minidle_ = (minidle * (int)nsecPerByte) / 8;
+	cl->minidle_ = (int)((int64_t)minidle * (int64_t)nsecPerByte / 8);
 	if (cl->minidle_ > 0)
 		cl->minidle_ = 0;
 #else