diff --git a/sys/bus/isa/pnp.c b/sys/bus/isa/pnp.c
--- a/sys/bus/isa/pnp.c
+++ b/sys/bus/isa/pnp.c
@@ -386,6 +386,7 @@
 			}
 			large_len = resp[0] + (resp[1] << 8);
 			resp += 2;
+			scanning -= 2;
 
 			if (scanning < large_len) {
 				scanning = 0;