diff --git a/Assembly.cpp b/Assembly.cpp
index 75d706f..976d304 100644
--- a/Assembly.cpp
+++ b/Assembly.cpp
@@ -848,7 +848,8 @@ void ha_overlap_and_correct(int round)
 		b[i] = ha_ovec_init(0, (round == asm_opt.number_of_round - 1));
     if(ha_idx) hom_cov = asm_opt.hom_cov;
 	if(ha_idx == NULL) ha_idx = ha_pt_gen(&asm_opt, ha_flt_tab, round == 0? 0 : 1, 0, &R_INF, &hom_cov, &het_cov); // build the index
-	if (round == 0 && ha_flt_tab == 0) // then asm_opt.hom_cov hasn't been updated
+	debug_adapter(&asm_opt, &R_INF);
+    if (round == 0 && ha_flt_tab == 0) // then asm_opt.hom_cov hasn't been updated
 		ha_opt_update_cov(&asm_opt, hom_cov);
 	if (asm_opt.required_read_name)
 		kt_for(asm_opt.thread_num, worker_ovec_related_reads, b, R_INF.total_reads);
diff --git a/htab.cpp b/htab.cpp
index dcbf9c9..fb40fe6 100644
--- a/htab.cpp
+++ b/htab.cpp
@@ -720,6 +720,48 @@ static void *worker_count(void *data, int step, void *in) // callback for kt_pip
 	return 0;
 }
 
+void debug_adapter(const hifiasm_opt_t *asm_opt, All_reads *rs)
+{
+    int ret;
+    uint32_t i, m, pass, unpass;
+    gzFile fp = 0;
+    kseq_t *ks = NULL;
+    UC_Read ucr;
+    init_UC_Read(&ucr);
+
+    for (i = m = pass = unpass = 0; i < (uint32_t)asm_opt->num_reads; ++i)
+    {
+        if ((fp = gzopen(asm_opt->read_file_names[i], "r")) == 0) continue;
+        ks = kseq_init(fp);
+        while ((ret = kseq_read(ks)) >= 0) 
+        {
+            int l = ks->seq.l;
+            if((l - asm_opt->adapterLen*2) <= 0) continue;
+            recover_UC_Read(&ucr, rs, m);
+            fprintf(stderr, "l: %d, ucr.length: %lld, asm_opt->adapterLen: %d\n", 
+            l, ucr.length, asm_opt->adapterLen);
+            if(memcmp(ucr.seq, ks->seq.s+asm_opt->adapterLen, ucr.length) == 0)
+            {
+                pass++;
+            }
+            else
+            {
+                unpass++;
+            }
+            m++;
+        }
+        kseq_destroy(ks);
+        gzclose(fp);
+        ks = NULL;
+        fp = 0;
+    }
+
+    destory_UC_Read(&ucr);
+
+    fprintf(stderr, "[M::%s::# reads: %u, # pass: %u, # unpass: %u\n]", __func__, m, pass, unpass);
+    exit(1);
+}
+
 static ha_ct_t *yak_count(const yak_copt_t *opt, const char *fn, int flag, ha_pt_t *p0, ha_ct_t *c0, const void *flt_tab, All_reads *rs, int64_t *n_seq)
 {
 	///for 0-th counting, flag = HAF_COUNT_ALL|HAF_RS_WRITE_LEN|HAF_CREATE_NEW
diff --git a/htab.h b/htab.h
index c6feba6..613fbea 100644
--- a/htab.h
+++ b/htab.h
@@ -62,6 +62,7 @@ void ha_triobin(const hifiasm_opt_t *opt);
 void ha_sketch(const char *str, int len, int w, int k, uint32_t rid, int is_hpc, ha_mz1_v *p, const void *hf);
 void ha_sketch_query(const char *str, int len, int w, int k, uint32_t rid, int is_hpc, ha_mz1_v *p, const void *hf, kvec_t_u8_warp* k_flag, kvec_t_u64_warp* dbg_ct);
 int ha_analyze_count(int n_cnt, const int64_t *cnt, int *peak_het);
+void debug_adapter(const hifiasm_opt_t *asm_opt, All_reads *rs);
 
 static inline uint64_t yak_hash64(uint64_t key, uint64_t mask) // invertible integer hash function
 {