diff --git a/.gitignore b/.gitignore
index e096c24a..312f6426 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,7 @@
 a.out
 *.log
 *.trs
+cov-int
 tmp
 tmp-*
 test/variables.sh
diff --git a/libvips/arithmetic/arithmetic.c b/libvips/arithmetic/arithmetic.c
index 0b6fe14d..6db74766 100644
--- a/libvips/arithmetic/arithmetic.c
+++ b/libvips/arithmetic/arithmetic.c
@@ -424,7 +424,7 @@ vips__formatalike( VipsImage *in1, VipsImage *in2,
 	in[0] = in1;
 	in[1] = in2;
 
-	if( vips__formatalike_vec( in, out, 2 ) )
+	if( vips__formatalike_vec( in, &out[0], 2 ) )
 		return( -1 );
 
 	*out1 = out[0];
@@ -443,7 +443,7 @@ vips__sizealike( VipsImage *in1, VipsImage *in2,
 	in[0] = in1;
 	in[1] = in2;
 
-	if( vips__sizealike_vec( in, out, 2 ) )
+	if( vips__sizealike_vec( in, &out[0], 2 ) )
 		return( -1 );
 
 	*out1 = out[0];
@@ -462,7 +462,7 @@ vips__bandalike( const char *domain,
 	in[0] = in1;
 	in[1] = in2;
 
-	if( vips__bandalike_vec( domain, in, out, 2, 1 ) )
+	if( vips__bandalike_vec( domain, in, &out[0], 2, 1 ) )
 		return( -1 );
 
 	*out1 = out[0];
diff --git a/libvips/foreign/openslide2vips.c b/libvips/foreign/openslide2vips.c
index 7a1258cf..42165ada 100644
--- a/libvips/foreign/openslide2vips.c
+++ b/libvips/foreign/openslide2vips.c
@@ -419,14 +419,12 @@ argb2rgba( uint32_t *buf, int n, uint32_t bg )
 		uint8_t a = x >> 24;
 		VipsPel *out = (VipsPel *) p;
 
-		if( a == 255 ) {
-			*p = GUINT32_TO_BE((x << 8) | 255);
-		} 
-		else if( a == 0 ) {
+		if( a == 255 ) 
+			*p = GUINT32_TO_BE( (x << 8) | 255 );
+		else if( a == 0 ) 
 			/* Use background color.
 			 */
-			*p = GUINT32_TO_BE((bg << 8) | 255);
-		}
+			*p = GUINT32_TO_BE( (bg << 8) | 255 );
 		else {
 			/* Undo premultiplication.
 			 */
diff --git a/libvips/foreign/radiance.c b/libvips/foreign/radiance.c
index f72f2a23..a1bc4e55 100644
--- a/libvips/foreign/radiance.c
+++ b/libvips/foreign/radiance.c
@@ -974,7 +974,7 @@ rad2vips_process_line( char *line, Read *read )
 		read->aspect *= aspectval( line );
 	}
 	else if( isprims( line ) ) {
-		primsval( read->prims, line );
+		(void) primsval( read->prims, line );
 	}
 
 	return( 0 );
diff --git a/libvips/foreign/tiff2vips.c b/libvips/foreign/tiff2vips.c
index 432ee1ce..b1a24127 100644
--- a/libvips/foreign/tiff2vips.c
+++ b/libvips/foreign/tiff2vips.c
@@ -1110,14 +1110,16 @@ parse_header( ReadTiff *rtiff, VipsImage *out )
 {
 	uint16 v;
 
-	TIFFGetFieldDefaulted( rtiff->tiff, TIFFTAG_SAMPLEFORMAT, &v );
+	rtiff->sample_format = SAMPLEFORMAT_INT;
 
-	/* Some images have this set to void, bizarre.
-	 */
-	if( v == SAMPLEFORMAT_VOID )
-		v = SAMPLEFORMAT_UINT;
+	if( TIFFGetFieldDefaulted( rtiff->tiff, TIFFTAG_SAMPLEFORMAT, &v ) ) {
+		/* Some images have this set to void, bizarre.
+		 */
+		if( v == SAMPLEFORMAT_VOID )
+			v = SAMPLEFORMAT_UINT;
 
-	rtiff->sample_format = v;
+		rtiff->sample_format = v;
+	}
 }
 
 	/* Arbitrary sanity-checking limits.
diff --git a/libvips/foreign/vips2jpeg.c b/libvips/foreign/vips2jpeg.c
index 4eb0e66d..10bae518 100644
--- a/libvips/foreign/vips2jpeg.c
+++ b/libvips/foreign/vips2jpeg.c
@@ -427,7 +427,7 @@ typedef void (*write_fn)( ExifData *ed,
 
 /* Write a tag. Update what's there, or make a new one.
  */
-static int
+static void
 write_tag( ExifData *ed, int ifd, ExifTag tag, write_fn fn, void *data )
 {
 	ExifEntry *entry;
@@ -448,8 +448,6 @@ write_tag( ExifData *ed, int ifd, ExifTag tag, write_fn fn, void *data )
 
 		fn( ed, entry, 0, data );
 	}
-
-	return( 0 );
 }
 
 /* This is different, we set the xres/yres from the vips header rather than
@@ -501,16 +499,12 @@ set_exif_resolution( ExifData *ed, VipsImage *im )
 	/* Main image xres/yres/unit are in ifd0. ifd1 has the thumbnail
 	 * xres/yres/unit.
 	 */
-	if( write_tag( ed, 0, EXIF_TAG_X_RESOLUTION, 
-		vips_exif_set_double, (void *) &xres ) ||
-		write_tag( ed, 0, EXIF_TAG_Y_RESOLUTION, 
-			vips_exif_set_double, (void *) &yres ) ||
-		write_tag( ed, 0, EXIF_TAG_RESOLUTION_UNIT, 
-			vips_exif_set_int, (void *) &unit ) ) {
-		vips_error( "VipsJpeg", 
-			"%s", _( "error setting JPEG resolution" ) );
-		return( -1 );
-	}
+	write_tag( ed, 0, EXIF_TAG_X_RESOLUTION, 
+		vips_exif_set_double, (void *) &xres );
+	write_tag( ed, 0, EXIF_TAG_Y_RESOLUTION, 
+		vips_exif_set_double, (void *) &yres );
+	write_tag( ed, 0, EXIF_TAG_RESOLUTION_UNIT, 
+		vips_exif_set_int, (void *) &unit );
 
 	return( 0 );
 }
@@ -523,14 +517,10 @@ set_exif_dimensions( ExifData *ed, VipsImage *im )
 	VIPS_DEBUG_MSG( "set_exif_dimensions: vips size of %d, %d\n",
 		im->Xsize, im->Ysize );
 
-	if( write_tag( ed, 2, EXIF_TAG_PIXEL_X_DIMENSION, 
-		vips_exif_set_int, (void *) &im->Xsize ) ||
-		write_tag( ed, 2, EXIF_TAG_PIXEL_Y_DIMENSION, 
-			vips_exif_set_int, (void *) &im->Ysize ) ) { 
-		vips_error( "VipsJpeg", 
-			"%s", _( "error setting JPEG dimensions" ) );
-		return( -1 );
-	}
+	write_tag( ed, 2, EXIF_TAG_PIXEL_X_DIMENSION, 
+		vips_exif_set_int, (void *) &im->Xsize );
+	write_tag( ed, 2, EXIF_TAG_PIXEL_Y_DIMENSION, 
+		vips_exif_set_int, (void *) &im->Ysize );
 
 	return( 0 );
 }
@@ -1324,10 +1314,15 @@ term_destination( j_compress_ptr cinfo )
 	 */
 	if( !(obuf = vips_malloc( NULL, len )) )
 		ERREXIT( cinfo, JERR_FILE_WRITE );
-	*(buf->obuf) = obuf;
-	*(buf->olen) = len;
+	else {
+		/* coverity doesn't know ERREXIT() does not return, so put
+		 * this in an else.
+		 */
+		*(buf->obuf) = obuf;
+		*(buf->olen) = len;
 
-	block_copy( buf->block, obuf );
+		block_copy( buf->block, obuf );
+	}
 }
 
 /* Set dest to one of our objects.
diff --git a/libvips/foreign/webp2vips.c b/libvips/foreign/webp2vips.c
index 1975df42..590ef38f 100644
--- a/libvips/foreign/webp2vips.c
+++ b/libvips/foreign/webp2vips.c
@@ -151,7 +151,7 @@ read_new( const char *filename, void *data, size_t length )
 		 *
 		 * mmap the input file, it's slightly quicker.
 		 */
-		if( !(read->fd = vips__open_image_read( read->filename )) ||
+		if( (read->fd = vips__open_image_read( read->filename )) < 0 ||
 			(read->length = vips_file_length( read->fd )) < 0 ||
 			!(read->data = vips__mmap( read->fd, 
 				FALSE, read->length, 0 )) ) {
diff --git a/libvips/iofuncs/buf.c b/libvips/iofuncs/buf.c
index d575085f..a067c158 100644
--- a/libvips/iofuncs/buf.c
+++ b/libvips/iofuncs/buf.c
@@ -528,19 +528,19 @@ vips_buf_append_size( VipsBuf *buf, size_t n )
 		 */
 		N_( "bytes" ), 
 
-		/* Kilo byte unit.
+		/* Kilobyte unit.
 		 */
 		N_( "KB" ), 
 
-		/* Mega byte unit.
+		/* Megabyte unit.
 		 */
 		N_( "MB" ), 
 
-		/* Giga byte unit.
+		/* Gigabyte unit.
 		 */
 		N_( "GB" ), 
 
-		/* Tera byte unit.
+		/* Terabyte unit.
 		 */
 		N_( "TB" ) 
 	};
@@ -548,14 +548,16 @@ vips_buf_append_size( VipsBuf *buf, size_t n )
 	double sz = n;
 	int i;
 
-	for( i = 0; sz > 1024 && i < VIPS_NUMBER( names ); sz /= 1024, i++ )
+	/* -1, since we want to stop at TB, not run off the end.
+	 */
+	for( i = 0; sz > 1024 && i < VIPS_NUMBER( names ) - 1; sz /= 1024, i++ )
 		;
 
 	if( i == 0 )
 		/* No decimal places for bytes.
 		 */
 		return( vips_buf_appendf( buf, "%g %s", sz, _( names[i] ) ) );
-	else
+	else 
 		return( vips_buf_appendf( buf, "%.2f %s", sz, _( names[i] ) ) );
 }
 
diff --git a/libvips/iofuncs/header.c b/libvips/iofuncs/header.c
index 105b5cef..db76dfd8 100644
--- a/libvips/iofuncs/header.c
+++ b/libvips/iofuncs/header.c
@@ -1503,30 +1503,29 @@ int
 vips_image_history_printf( VipsImage *image, const char *fmt, ... )
 {
 	va_list args;
-	char line[VIPS_PATH_MAX];
+	char str[VIPS_PATH_MAX];
+	VipsBuf buf = VIPS_BUF_STATIC( str );
 	time_t timebuf;
 
-	/* Format command. -40, to leave 26 for the ctime, three for the # and
-	 * a bit.
-	 */
 	va_start( args, fmt );
-	(void) vips_vsnprintf( line, VIPS_PATH_MAX - 40, fmt, args );
+	(void) vips_buf_vappendf( &buf, fmt, args );
 	va_end( args );
-	strcat( line, " # " );
+	vips_buf_appends( &buf, " # " );
 
 	/* Add the date. ctime always attaches a '\n', gah.
 	 */
 	time( &timebuf );
-	strcat( line, ctime( &timebuf ) );
-	line[strlen( line ) - 1] = '\0';
+	vips_buf_appends( &buf, ctime( &timebuf ) ); 
+	vips_buf_removec( &buf, '\n' ); 
 
 #ifdef DEBUG
 	printf( "vips_image_history_printf: "
-		"adding:\n\t%s\nto history on image %p\n", line, image );
+		"adding:\n\t%s\nto history on image %p\n", 
+		vips_buf_all( &buf ), image );
 #endif /*DEBUG*/
 
 	image->history_list = g_slist_append( image->history_list, 
-		vips__gvalue_ref_string_new( line ) );
+		vips__gvalue_ref_string_new( vips_buf_all( &buf ) ) );
 
 	return( 0 );
 }
diff --git a/libvips/iofuncs/region.c b/libvips/iofuncs/region.c
index 52c11908..aad8f3bf 100644
--- a/libvips/iofuncs/region.c
+++ b/libvips/iofuncs/region.c
@@ -363,7 +363,7 @@ vips_region_sanity( VipsObject *object, VipsBuf *buf )
 {
 	VipsRegion *region = VIPS_REGION( object );
 
-	vips_object_sanity( VIPS_OBJECT( region->im ) );
+	(void) vips_object_sanity( VIPS_OBJECT( region->im ) );
 
 	switch( region->im->dtype ) { 
 	case VIPS_IMAGE_PARTIAL:
diff --git a/libvips/iofuncs/util.c b/libvips/iofuncs/util.c
index 15d380b2..69686d33 100644
--- a/libvips/iofuncs/util.c
+++ b/libvips/iofuncs/util.c
@@ -1688,6 +1688,7 @@ vips__substitute( char *buf, size_t len, char *sub )
 				n = atoi( p + 1 );
 				if( lowest_n == -1 ||
 					n < lowest_n ) {
+					lowest_n = n;
 					sub_start = p;
 					sub_end = q + 1;
 				}
diff --git a/libvips/mosaicing/im_initialize.c b/libvips/mosaicing/im_initialize.c
index d4eda738..0b57e319 100644
--- a/libvips/mosaicing/im_initialize.c
+++ b/libvips/mosaicing/im_initialize.c
@@ -74,9 +74,14 @@ im__initialize( TIE_POINTS *points )
 				++j;
 			}
 
-		xdelta = xdelta/j;
-		ydelta = ydelta/j;
-		for(i = 0; i < npt; i++ ) {
+		if( j == 0 ) {
+			vips_error( "im_initialize", "no tie points" );
+			return( -1 );
+		}
+
+		xdelta = xdelta / j;
+		ydelta = ydelta / j;
+		for( i = 0; i < npt; i++ ) {
 			dx[i] = (xsec[i] - xref[i]) - xdelta;
 			dy[i] = (ysec[i] - yref[i]) - ydelta;
 		}
@@ -84,7 +89,7 @@ im__initialize( TIE_POINTS *points )
 		for( i = 0; i < npt; i++ ) {
 			a1 = dx[i];
 			a2 = dy[i];
-			points->deviation[i] = sqrt( a1*a1 + a2*a2 );
+			points->deviation[i] = sqrt( a1 * a1 + a2 * a2 );
 		}	
 
 		points->l_scale = 1.0;
diff --git a/libvips/resample/affine.c b/libvips/resample/affine.c
index 564e159a..6274ceb4 100644
--- a/libvips/resample/affine.c
+++ b/libvips/resample/affine.c
@@ -430,6 +430,12 @@ vips_affine_build( VipsObject *object )
 			"interpolate", interpolate,
 			NULL ); 
 		g_object_unref( interpolate );
+
+		/* coverity gets confused by this, it thinks
+		 * affine->interpolate may still be null. Assign ourselves,
+		 * even though we don't need to.
+		 */
+		affine->interpolate = interpolate;
 	}
 
 	in = resample->in;
@@ -492,7 +498,7 @@ vips_affine_build( VipsObject *object )
 	/* Check for coordinate overflow ... we want to be able to hold the
 	 * output space inside INT_MAX / TRANSFORM_SCALE.
 	 */
-	edge = INT_MAX / VIPS_TRANSFORM_SCALE;
+	edge = (int) (INT_MAX / VIPS_TRANSFORM_SCALE);
 	if( affine->trn.oarea.left < -edge || 
 		affine->trn.oarea.top < -edge ||
 		VIPS_RECT_RIGHT( &affine->trn.oarea ) > edge ||