diff --git a/main.c b/main.c
index d9008f2..c27d6e9 100644
--- a/main.c
+++ b/main.c
@@ -10,7 +10,7 @@
 #include "minimap.h"
 #include "mmpriv.h"
 
-#define MM_VERSION "2.0-r169-pre"
+#define MM_VERSION "2.0-r170-pre"
 
 void liftrlimit()
 {
@@ -48,6 +48,7 @@ static struct option long_options[] = {
 	{ "no-kalloc",      no_argument,       0, 0 },
 	{ "print-qname",    no_argument,       0, 0 },
 	{ "no-self",        no_argument,       0, 0 },
+	{ "print-seed",     no_argument,       0, 0 },
 	{ "version",        no_argument,       0, 'V' },
 	{ "min-count",      required_argument, 0, 'n' },
 	{ "min-chain-score",required_argument, 0, 'm' },
@@ -100,7 +101,8 @@ int main(int argc, char *argv[])
 		else if (c == 0 && long_idx == 2) keep_name = 0; // --int-rname
 		else if (c == 0 && long_idx == 3) mm_dbg_flag |= MM_DBG_NO_KALLOC; // --no-kalloc
 		else if (c == 0 && long_idx == 4) mm_dbg_flag |= MM_DBG_PRINT_QNAME; // --print-qname
-		else if (c == 0 && long_idx == 5) opt.flag |= MM_F_NO_SELF;
+		else if (c == 0 && long_idx == 5) opt.flag |= MM_F_NO_SELF; // --no-self
+		else if (c == 0 && long_idx == 6) mm_dbg_flag |= MM_DBG_PRINT_QNAME | MM_DBG_PRINT_SEED; // --print-seed
 		else if (c == 'V') {
 			puts(MM_VERSION);
 			return 0;
diff --git a/map.c b/map.c
index 8ca14b8..2e42dd1 100644
--- a/map.c
+++ b/map.c
@@ -236,6 +236,10 @@ mm_reg1_t *mm_map_frag(const mm_mapopt_t *opt, const mm_idx_t *mi, mm_tbuf_t *b,
 		if (m[i].is_alloc) kfree(b->km, m[i].x.r);
 	kfree(b->km, m);
 
+	if (mm_dbg_flag & MM_DBG_PRINT_SEED)
+		for (i = 0; i < n_a; ++i)
+			fprintf(stderr, "SD\t%d\t%c\t%s\t%d\t%d\n", (int32_t)a[i].y, "+-"[a[i].x>>63], mi->seq[a[i].x<<1>>33].name, (int32_t)a[i].x, (int32_t)(a[i].y>>32&0xff));
+
 	n_u = mm_chain_dp(opt->max_gap, opt->bw, opt->max_chain_skip, opt->min_cnt, opt->min_chain_score, n_a, a, &u, b->km);
 	regs = mm_gen_regs(b->km, qlen, n_u, u, a);
 	*n_regs = n_u;
@@ -296,7 +300,7 @@ static void worker_for(void *_data, long i, int tid) // kt_for() callback
 {
     step_t *step = (step_t*)_data;
 	if (mm_dbg_flag & MM_DBG_PRINT_QNAME)
-		fprintf(stderr, "Processing query %s on thread %d\n", step->seq[i].name, tid);
+		fprintf(stderr, "QR\t%s\t%d\n", step->seq[i].name, tid);
 	step->reg[i] = mm_map(step->p->mi, step->seq[i].l_seq, step->seq[i].seq, &step->n_reg[i], step->buf[tid], step->p->opt, step->seq[i].name);
 }
 
diff --git a/mmpriv.h b/mmpriv.h
index 8d1b8d8..6fff097 100644
--- a/mmpriv.h
+++ b/mmpriv.h
@@ -10,6 +10,7 @@
 
 #define MM_DBG_NO_KALLOC   0x1
 #define MM_DBG_PRINT_QNAME 0x2
+#define MM_DBG_PRINT_SEED  0x4
 
 #ifndef kroundup32
 #define kroundup32(x) (--(x), (x)|=(x)>>1, (x)|=(x)>>2, (x)|=(x)>>4, (x)|=(x)>>8, (x)|=(x)>>16, ++(x))