diff --git a/bwamem.c b/bwamem.c
index ae1886a..fe0ecbe 100644
--- a/bwamem.c
+++ b/bwamem.c
@@ -550,7 +550,7 @@ void bwa_hit2sam(kstring_t *str, const int8_t mat[25], int q, int r, int w, cons
 		if (mid == rid) {
 			int64_t p0 = p->rb < bns->l_pac? p->rb : (bns->l_pac<<1) - 1 - p->rb;
 			int64_t p1 = m->rb < bns->l_pac? m->rb : (bns->l_pac<<1) - 1 - m->rb;
-			kputw(p0 - p1, str);
+			kputw(p0 - p1 + (p0 > p1? 1 : -1), str);
 		} else kputw(0, str);
 		kputc('\t', str);
 	} else kputsn("\t*\t0\t0\t", 7, str);