diff --git a/hit.c b/hit.c
index ebc0f68..a8d0f42 100644
--- a/hit.c
+++ b/hit.c
@@ -126,9 +126,20 @@ void mm_hit_sort_by_dp(void *km, int *n_regs, mm_reg1_t *r)
 	kfree(km, t);
 }
 
+int mm_set_sam_pri(int n, mm_reg1_t *r)
+{
+	int i, n_pri = 0;
+	for (i = 0; i < n; ++i)
+		if (r[i].id == r[i].parent) {
+			++n_pri;
+			r[i].sam_pri = (n_pri == 1);
+		} else r[i].sam_pri = 0;
+	return n_pri;
+}
+
 void mm_sync_regs(void *km, int n_regs, mm_reg1_t *regs) // keep mm_reg1_t::{id,parent} in sync; also reset id
 {
-	int *tmp, i, max_id = -1, n_tmp, n_pri;
+	int *tmp, i, max_id = -1, n_tmp;
 	if (n_regs <= 0) return;
 	for (i = 0; i < n_regs; ++i) // NB: doesn't work if mm_reg1_t::id is negative
 		max_id = max_id > regs[i].id? max_id : regs[i].id;
@@ -137,7 +148,7 @@ void mm_sync_regs(void *km, int n_regs, mm_reg1_t *regs) // keep mm_reg1_t::{id,
 	for (i = 0; i < n_tmp; ++i) tmp[i] = -1;
 	for (i = 0; i < n_regs; ++i)
 		if (regs[i].id >= 0) tmp[regs[i].id] = i;
-	for (i = n_pri = 0; i < n_regs; ++i) {
+	for (i = 0; i < n_regs; ++i) {
 		mm_reg1_t *r = &regs[i];
 		r->id = i;
 		if (r->parent == MM_PARENT_TMP_PRI)
@@ -145,11 +156,9 @@ void mm_sync_regs(void *km, int n_regs, mm_reg1_t *regs) // keep mm_reg1_t::{id,
 		else if (r->parent >= 0 && tmp[r->parent] >= 0)
 			r->parent = tmp[r->parent];
 		else r->parent = MM_PARENT_UNSET;
-		if (r->id == r->parent) {
-			if (n_pri++ == 0) r->sam_pri = 1;
-		}
 	}
 	kfree(km, tmp);
+	mm_set_sam_pri(n_regs, regs);
 }
 
 void mm_select_sub(void *km, float mask_level, float pri_ratio, int best_n, int *n_, mm_reg1_t *r)
diff --git a/main.c b/main.c
index eda7d6f..6b15266 100644
--- a/main.c
+++ b/main.c
@@ -10,7 +10,7 @@
 #include "minimap.h"
 #include "mmpriv.h"
 
-#define MM_VERSION "2.0-r151-pre"
+#define MM_VERSION "2.0-r153-pre"
 
 void liftrlimit()
 {
diff --git a/map.c b/map.c
index bb84703..1b2f1d1 100644
--- a/map.c
+++ b/map.c
@@ -249,6 +249,7 @@ mm_reg1_t *mm_map_frag(const mm_mapopt_t *opt, const mm_idx_t *mi, mm_tbuf_t *b,
 		if (!(opt->flag & MM_F_AVA)) {
 			mm_set_parent(b->km, opt->mask_level, *n_regs, regs);
 			mm_select_sub(b->km, opt->mask_level, opt->pri_ratio, opt->best_n, n_regs, regs);
+			mm_set_sam_pri(*n_regs, regs);
 		}
 	}
 	mm_set_mapq(*n_regs, regs);
diff --git a/mmpriv.h b/mmpriv.h
index 6f7c48d..8d1b8d8 100644
--- a/mmpriv.h
+++ b/mmpriv.h
@@ -42,6 +42,7 @@ mm_reg1_t *mm_align_skeleton(void *km, const mm_mapopt_t *opt, const mm_idx_t *m
 mm_reg1_t *mm_gen_regs(void *km, int qlen, int n_u, uint64_t *u, mm128_t *a);
 void mm_split_reg(mm_reg1_t *r, mm_reg1_t *r2, int n, int qlen, mm128_t *a);
 void mm_sync_regs(void *km, int n_regs, mm_reg1_t *regs);
+int mm_set_sam_pri(int n, mm_reg1_t *r);
 void mm_set_parent(void *km, float mask_level, int n, mm_reg1_t *r);
 void mm_select_sub(void *km, float mask_level, float pri_ratio, int best_n, int *n_, mm_reg1_t *r);
 void mm_filter_regs(void *km, const mm_mapopt_t *opt, int *n_regs, mm_reg1_t *regs);