diff --git a/python/cmappy.h b/python/cmappy.h
index ae2428e..082b324 100644
--- a/python/cmappy.h
+++ b/python/cmappy.h
@@ -119,9 +119,9 @@ static char *mappy_fetch_seq(const mm_idx_t *mi, const char *name, int st, int e
 	*len = 0;
 	rid = mm_idx_name2id(mi, name);
 	if (rid < 0) return 0;
-	if (st >= mi->seq[i].len || st >= en) return 0;
-	if (en < 0 || en > mi->seq[i].len)
-		en = mi->seq[i].len;
+	if (st >= mi->seq[rid].len || st >= en) return 0;
+	if (en < 0 || en > mi->seq[rid].len)
+		en = mi->seq[rid].len;
 	s = (char*)malloc(en - st + 1);
 	*len = mm_idx_getseq(mi, rid, st, en, s);
 	for (i = 0; i < *len; ++i)