diff --git a/btpd/net.c b/btpd/net.c
index 6d1d220..e627378 100644
--- a/btpd/net.c
+++ b/btpd/net.c
@@ -766,6 +766,7 @@ net_generic_read(struct peer *p, unsigned long rmax)
     }
     if (off != len) {
 	gr->iob.buf_off = len - off;
+        assert(gr->iob.buf_off <= gr->iob.buf_len);
 	bcopy(buf + off, gr->iob.buf, gr->iob.buf_off);
     }
     event_add(&p->in_ev, NULL);
diff --git a/btpd/net.h b/btpd/net.h
index 5a2c704..7216362 100644
--- a/btpd/net.h
+++ b/btpd/net.h
@@ -65,7 +65,7 @@ struct handshake {
     char _io_buf[SHAKE_LEN];
 };
 
-#define MAX_INPUT_LEFT 12
+#define MAX_INPUT_LEFT 16
 
 struct generic_reader {
     struct input_reader rd;