diff --git a/ChangeLog b/ChangeLog
index 6535460f..3494b24b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -7,6 +7,7 @@
 - fix regression in tiff pyramid thumbnailing [tand826]
 - stop 0-length buffer being passed to imagemagick [lovell]
 - convert no-profile CMYK to RGB on save [augustocdias]
+- ensure SVG loader skips input with chars outside x09-x7F range [lovell]
 
 24/1/20 started 8.10.0
 - more conformat IIIF output from dzsave [regisrob]
diff --git a/libvips/conversion/arrayjoin.c b/libvips/conversion/arrayjoin.c
index 5f140408..40720fc3 100644
--- a/libvips/conversion/arrayjoin.c
+++ b/libvips/conversion/arrayjoin.c
@@ -424,7 +424,10 @@ vips_arrayjoinv( VipsImage **in, VipsImage **out, int n, va_list ap )
  * Smallest common format in 
  * <link linkend="libvips-arithmetic">arithmetic</link>).
  *
- * See also: vips_join(), vips_insert().
+ * vips_colourspace() can be useful for moving the images to a common
+ * colourspace for compositing.
+ *
+ * See also: vips_join(), vips_insert(), vips_colourspace().
  *
  * Returns: 0 on success, -1 on error
  */
diff --git a/libvips/include/vips/internal.h b/libvips/include/vips/internal.h
index 84030580..d549c321 100644
--- a/libvips/include/vips/internal.h
+++ b/libvips/include/vips/internal.h
@@ -114,7 +114,6 @@ void vips__threadpool_init( void );
 
 void vips__cache_init( void );
 
-void vips__sink_screen_init( void );
 void vips__print_renders( void );
 
 void vips__type_leak( void );
diff --git a/libvips/iofuncs/init.c b/libvips/iofuncs/init.c
index 7c9cd5d9..aa1b5901 100644
--- a/libvips/iofuncs/init.c
+++ b/libvips/iofuncs/init.c
@@ -413,7 +413,6 @@ vips_init( const char *argv0 )
 #endif /*HAVE_THREAD_NEW*/
 
 	vips__threadpool_init();
-	vips__sink_screen_init();
 	vips__buffer_init();
 	vips__meta_init();
 
diff --git a/libvips/iofuncs/sinkscreen.c b/libvips/iofuncs/sinkscreen.c
index a2dfaee5..03001d2f 100644
--- a/libvips/iofuncs/sinkscreen.c
+++ b/libvips/iofuncs/sinkscreen.c
@@ -450,6 +450,9 @@ vips__render_shutdown( void )
 		}
 		else
 			g_mutex_unlock( render_dirty_lock );
+
+		VIPS_FREEF( vips_g_mutex_free, render_dirty_lock );
+		vips_semaphore_destroy( &n_render_dirty_sem );
 	}
 
 	VIPS_FREEF( vips_g_mutex_free, render_dirty_lock );
@@ -1030,8 +1033,8 @@ render_thread_main( void *client )
 	return( NULL );
 }
 
-void
-vips__sink_screen_init( void )
+static void *
+vips__sink_screen_init( void *data )
 {
 	g_assert( !render_thread ); 
 	g_assert( !render_dirty_lock ); 
@@ -1040,6 +1043,8 @@ vips__sink_screen_init( void )
 	vips_semaphore_init( &n_render_dirty_sem, 0, "n_render_dirty" );
 	render_thread = vips_g_thread_new( "sink_screen",
 		render_thread_main, NULL );
+
+	return( NULL );
 }
 
 /**
@@ -1099,8 +1104,12 @@ vips_sink_screen( VipsImage *in, VipsImage *out, VipsImage *mask,
 	int priority,
 	VipsSinkNotify notify_fn, void *a )
 {
+	static GOnce once = G_ONCE_INIT;
+
 	Render *render;
 
+	VIPS_ONCE( &once, vips__sink_screen_init, NULL );
+
 	if( tile_width <= 0 || tile_height <= 0 || 
 		max_tiles < -1 ) {
 		vips_error( "vips_sink_screen", "%s", _( "bad parameters" ) );