diff --git a/ChangeLog b/ChangeLog
index 1d13362d..df7f6800 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -12,6 +12,9 @@
 - rename 'disc' as 'memory' and default off
 - add vips_find_trim(), search for non-background areas 
 
+2/8/17 started 8.5.8
+- fix transparency detection in merge, thanks Haida
+
 9/6/17 started 8.5.7
 - better smartcrop
 - transform cmyk->rgb automatically on write if there's an embedded profile
diff --git a/configure.ac b/configure.ac
index 7ed71f17..cf05d455 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2,7 +2,11 @@
 
 # also update the version number in the m4 macros below
 
+<<<<<<< HEAD
 AC_INIT([vips], [8.6.0], [vipsip@jiscmail.ac.uk])
+=======
+AC_INIT([vips], [8.5.8], [vipsip@jiscmail.ac.uk])
+>>>>>>> 8.5
 # required for gobject-introspection
 AC_PREREQ(2.62)
 
diff --git a/libvips/mosaicing/im_lrmerge.c b/libvips/mosaicing/im_lrmerge.c
index 5ce599ea..cdb012cc 100644
--- a/libvips/mosaicing/im_lrmerge.c
+++ b/libvips/mosaicing/im_lrmerge.c
@@ -392,7 +392,7 @@ make_firstlast( MergeInfo *inf, Overlapping *ovlap, Rect *oreg )
 	int ii; \
 	\
 	for( ii = 0; ii < cb; ii++ ) \
-		if( tt[i] ) \
+		if( tt[i + ii] ) \
 			break; \
 	if( ii == cb )  \
 		(RESULT) = 1; \
diff --git a/libvips/mosaicing/im_tbmerge.c b/libvips/mosaicing/im_tbmerge.c
index 38079b25..09afb6ff 100644
--- a/libvips/mosaicing/im_tbmerge.c
+++ b/libvips/mosaicing/im_tbmerge.c
@@ -335,7 +335,7 @@ make_firstlast( MergeInfo *inf, Overlapping *ovlap, Rect *oreg )
 	int ii; \
 	\
 	for( ii = 0; ii < cb; ii++ ) \
-		if( tt[i] ) \
+		if( tt[i + ii] ) \
 			break; \
 	if( ii == cb )  \
 		(RESULT) = 1; \