diff --git a/Makefile b/Makefile
index 5aa07c5..ce2a397 100644
--- a/Makefile
+++ b/Makefile
@@ -1,8 +1,7 @@
 CC=			gcc
-CFLAGS=		-g -Wall -O2 -msse2
-CXXFLAGS=	$(CFLAGS)
+CFLAGS=		-g -Wall -O2
 AR=			ar
-DFLAGS=		-DHAVE_PTHREAD #-D_NO_SSE2 #-D_FILE_OFFSET_BITS=64
+DFLAGS=		-DHAVE_PTHREAD
 LOBJS=		utils.o kstring.o ksw.o bwt.o bntseq.o bwa.o bwamem.o bwamem_pair.o
 AOBJS=		QSufSort.o bwt_gen.o bwase.o bwaseqio.o bwtgap.o bwtaln.o bamlite.o \
 			is.o bwtindex.o bwape.o kopen.o pemerge.o \
@@ -17,8 +16,6 @@ SUBDIRS=	.
 
 .c.o:
 		$(CC) -c $(CFLAGS) $(DFLAGS) $(INCLUDES) $< -o $@
-.cc.o:
-		$(CXX) -c $(CXXFLAGS) $(DFLAGS) $(INCLUDES) $< -o $@
 
 all:$(PROG)
 
diff --git a/NEWS b/NEWS
index 35202f1..7474726 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,49 @@
+Release 0.7.2 (9 March, 2013)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Emergent bug fix: 0.7.0 and 0.7.1 give a wrong sign to TLEN. In addition,
+flagging `properly paired' also gets improved a little.
+
+(0.7.2: 9 March 2013, r351)
+
+
+
+Release 0.7.1 (8 March, 2013)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Changes to BWA-MEM:
+
+ * Bugfix: rare segmentation fault caused by a partial hit to the end of the
+   last sequence.
+
+ * Bugfix: occasional mis-pairing given an interleaved fastq.
+
+ * Bugfix: wrong mate information when the mate is unmapped. SAM generated by
+   BWA-MEM can now be validated with Picard.
+
+ * Improved the performance and accuracy for ultra-long query sequences.
+   Short-read alignment is not affected.
+
+Changes to other components:
+
+ * In BWA-backtrack and BWA-SW, replaced the code for global alignment,
+   Smith-Waterman and SW extension. The performance and accuracy of the two
+   algorithms stay the same.
+
+ * Added an experimental subcommand to merge overlapping paired ends. The
+   algorithm is very conservative: it may miss true overlaps but rarely makes
+   mistakes.
+
+An important note is that like BWA-SW, BWA-MEM may output multiple primary
+alignments for a read, which may cause problems to some tools. For aligning
+sequence reads, it is advised to use `-M' to flag extra hits as secondary. This
+option is not the default because multiple primary alignments are theoretically
+possible in sequence alignment.
+
+(0.7.1: 8 March 2013, r347)
+
+
+
 Beta Release 0.7.0 (28 Feburary, 2013)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -16,14 +62,14 @@ In addition to the algorithmic improvements, BWA-MEM also implements a few
 handy features in practical aspects:
 
  1. BWA-MEM automatically switches between local and glocal (global wrt reads;
-	local wrt reference) alignment. It reports the end-to-end glocal alignment
-	if the glocal alignment is not much worse than the optimal local alignment.
-	Glocal alignment reduces reference bias.
+    local wrt reference) alignment. It reports the end-to-end glocal alignment
+    if the glocal alignment is not much worse than the optimal local alignment.
+    Glocal alignment reduces reference bias.
 
  2. BWA-MEM automatically infers pair orientation from a batch of single-end
     alignments. It allows more than one orientations if there are sufficient
-	supporting reads. This feature has not been tested on reads from Illumina
-	jumping library yet. (EXPERIMENTAL)
+    supporting reads. This feature has not been tested on reads from Illumina
+    jumping library yet. (EXPERIMENTAL)
 
  3. BWA-MEM optionally takes one interleaved fastq for paired-end mapping. It
     is possible to convert a name-sorted BAM to an interleaved fastq on the fly
@@ -37,8 +83,8 @@ handy features in practical aspects:
     files without replying on bash features.
 
  6. BWA-MEM provides a few basic APIs for single-end mapping. The `example.c'
-	program in the source code directory implements a full single-end mapper in
-	50 lines of code.
+    program in the source code directory implements a full single-end mapper in
+    50 lines of code.
 
 The BWA-MEM algorithm is in the beta phase. It is not advised to use BWA-MEM
 for production use yet. However, when the implementation becomes stable after a
diff --git a/bwa.1 b/bwa.1
index b1bbb2a..8e90848 100644
--- a/bwa.1
+++ b/bwa.1
@@ -1,4 +1,4 @@
-.TH bwa 1 "10 March 2013" "bwa-0.7.1" "Bioinformatics tools"
+.TH bwa 1 "9 March 2013" "bwa-0.7.2" "Bioinformatics tools"
 .SH NAME
 .PP
 bwa - Burrows-Wheeler Alignment Tool
@@ -235,7 +235,7 @@ attached to every read in the output. An example is '@RG\\tID:foo\\tSM:bar'.
 .BI -T \ INT
 Don't output alignment with score lower than
 .IR INT .
-This option only affects output. [30]
+This option affects output and occasionally SAM flag 2. [30]
 .TP
 .B -a
 Output all found alignments for single-end or unpaired paired-end reads. These
diff --git a/bwa.c b/bwa.c
index 722ca4d..a0ed448 100644
--- a/bwa.c
+++ b/bwa.c
@@ -75,9 +75,9 @@ void bwa_fill_scmat(int a, int b, int8_t mat[25])
 	for (i = k = 0; i < 4; ++i) {
 		for (j = 0; j < 4; ++j)
 			mat[k++] = i == j? a : -b;
-		mat[k++] = 0; // ambiguous base
+		mat[k++] = -1; // ambiguous base
 	}
-	for (j = 0; j < 5; ++j) mat[k++] = 0;
+	for (j = 0; j < 5; ++j) mat[k++] = -1;
 }
 
 // Generate CIGAR when the alignment end points are known
diff --git a/bwamem.c b/bwamem.c
index 78d77d0..a564b86 100644
--- a/bwamem.c
+++ b/bwamem.c
@@ -612,7 +612,7 @@ void bwa_hit2sam(kstring_t *str, const int8_t mat[25], int q, int r, int w, cons
 #define is_mapped(x) ((x)->rb >= 0 && (x)->rb < (x)->re && (x)->re <= bns->l_pac<<1)
 	int score, n_cigar, is_rev = 0, rid, mid, copy_mate = 0, NM = -1;
 	uint32_t *cigar = 0;
-	int64_t pos;
+	int64_t pos = -1;
 	bwahit_t ptmp, *p = &ptmp;
 
 	if (!p_) { // in this case, generate an unmapped alignment
@@ -628,6 +628,7 @@ void bwa_hit2sam(kstring_t *str, const int8_t mat[25], int q, int r, int w, cons
 	}
 	p->flag |= p->rb >= bns->l_pac? 0x10 : 0; // is reverse strand
 	p->flag |= m && m->rb >= bns->l_pac? 0x20 : 0; // is mate on reverse strand
+	if (is_mapped(p) && m && !is_mapped(m) && (p->flag&0x10)) p->flag |= 0x20; // if mate is unmapped, it takes the strand of the current read
 	kputs(s->name, str); kputc('\t', str);
 	if (is_mapped(p)) { // has a coordinate, no matter whether it is mapped or copied from the mate
 		int sam_flag = p->flag&0xff; // the flag that will be outputed to SAM; it is not always the same as p->flag
@@ -670,9 +671,13 @@ 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 + (p0 > p1? 1 : -1), str);
+			kputw(-(p0 - p1 + (p0 > p1? 1 : p0 < p1? -1 : 0)), str);
 		} else kputw(0, str);
 		kputc('\t', str);
+	} else if (m && is_mapped(p)) { // then copy the position
+		kputsn("\t=\t", 3, str);
+		kputuw(pos - bns->anns[rid].offset + 1, str);
+		kputsn("\t0\t", 3, str);
 	} else kputsn("\t*\t0\t0\t", 7, str);
 	if (p->flag&0x100) { // for secondary alignments, don't write SEQ and QUAL
 		kputsn("*\t*", 3, str);
@@ -760,7 +765,12 @@ void mem_sam_se(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac, b
 			else if (h.qual > mapq0) h.qual = mapq0;
 			bwa_hit2sam(&str, opt->mat, opt->q, opt->r, p->w, bns, pac, s, &h, opt->flag&MEM_F_HARDCLIP, m);
 		}
-	} else bwa_hit2sam(&str, opt->mat, opt->q, opt->r, opt->w, bns, pac, s, 0, opt->flag&MEM_F_HARDCLIP, m);
+	} else {
+		bwahit_t h;
+		memset(&h, 0, sizeof(bwahit_t));
+		h.rb = h.re = -1; h.flag = extra_flag;
+		bwa_hit2sam(&str, opt->mat, opt->q, opt->r, opt->w, bns, pac, s, &h, opt->flag&MEM_F_HARDCLIP, m);
+	}
 	s->sam = str.s;
 }
 
diff --git a/bwamem_pair.c b/bwamem_pair.c
index 837666b..3b70cef 100644
--- a/bwamem_pair.c
+++ b/bwamem_pair.c
@@ -260,7 +260,7 @@ int mem_sam_pe(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac, co
 		// check if an end has multiple hits even after mate-SW
 		for (i = 0; i < 2; ++i) {
 			for (j = 1; j < a[i].n; ++j)
-				if (a[i].a[j].secondary < 0) break;
+				if (a[i].a[j].secondary < 0 && a[i].a[j].score >= opt->T) break;
 			is_multi[i] = j < a[i].n? 1 : 0;
 		}
 		if (is_multi[0] || is_multi[1]) goto no_pairing; // TODO: in rare cases, the true hit may be long but with low score
@@ -306,7 +306,11 @@ no_pairing:
 		if (a[i].n && a[i].a[0].score >= opt->T) {
 			mem_alnreg2hit(&a[i].a[0], &h[i]);
 			bwa_fix_xref(opt->mat, opt->q, opt->r, opt->w, bns, pac, (uint8_t*)s[i].seq, &h[i].qb, &h[i].qe, &h[i].rb, &h[i].re);
-		} else h[i].rb = h[i].re = -1;
+		} else {
+			memset(&h[i], 0, sizeof(bwahit_t));
+			h[i].rb = h[i].re = -1;
+			h[i].flag = 1<<(6+i) | 1;
+		}
 	}
 	mem_sam_se(opt, bns, pac, &s[0], &a[0], 0x41, &h[1]);
 	mem_sam_se(opt, bns, pac, &s[1], &a[1], 0x81, &h[0]);
diff --git a/bwt.h b/bwt.h
index e7b0f97..c36bf9b 100644
--- a/bwt.h
+++ b/bwt.h
@@ -29,6 +29,7 @@
 #define BWA_BWT_H
 
 #include <stdint.h>
+#include <stddef.h>
 
 // requirement: (OCC_INTERVAL%16 == 0); please DO NOT change this line because some part of the code assume OCC_INTERVAL=0x80
 #define OCC_INTV_SHIFT 7
diff --git a/bwtsw2_aux.c b/bwtsw2_aux.c
index bcb0bcb..88c13c7 100644
--- a/bwtsw2_aux.c
+++ b/bwtsw2_aux.c
@@ -153,7 +153,7 @@ void bsw2_extend_rght(const bsw2opt_t *opt, bwtsw2_t *b, uint8_t *query, int lq,
 		for (k = p->k, j = 0; k < p->k + lt && k < l_pac; ++k)
 			target[j++] = pac[k>>2] >> (~k&3)*2 & 0x3;
 		lt = j;
-		score = ksw_extend(lq - p->beg, &query[p->beg], lt, target, 5, mat, opt->q, opt->r, opt->bw, -1, 1, &qle, &tle, 0, 0, 0);
+		score = ksw_extend(lq - p->beg, &query[p->beg], lt, target, 5, mat, opt->q, opt->r, opt->bw, -1, 1, &qle, &tle, 0, 0, 0) - 1;
 //		if (score < p->G) fprintf(stderr, "[bsw2_extend_hits] %d < %d\n", score, p->G);
 		if (score >= p->G) {
 			p->G = score;
diff --git a/main.c b/main.c
index 20f0a02..090c194 100644
--- a/main.c
+++ b/main.c
@@ -3,7 +3,7 @@
 #include "utils.h"
 
 #ifndef PACKAGE_VERSION
-#define PACKAGE_VERSION "0.7.0-r341-beta"
+#define PACKAGE_VERSION "0.7.2-r351"
 #endif
 
 int bwa_fa2pac(int argc, char *argv[]);