diff --git a/ChangeLog b/ChangeLog
index b5c04f7c..3be50ed7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,9 @@
 xx/1/23 8.14.1
 
 - add vips_thread_isworker() compatibility function [remicollet]
+- add vips_semaphore_down_timeout() [kleisauke]
+- idle threads are removed after 15s [kleisauke]
+- fix version number in gtk-doc index [kleisauke]
 
 22/12/22 8.14.0
 
diff --git a/libvips/deprecated/rename.c b/libvips/deprecated/rename.c
index e3bc987e..476fa548 100644
--- a/libvips/deprecated/rename.c
+++ b/libvips/deprecated/rename.c
@@ -829,3 +829,11 @@ vips_free( void *buf )
 	return( 0 );
 }
 
+/* Use vips_thread_isvips() instead.
+ */
+gboolean
+vips_thread_isworker( void )
+{
+	return( vips_thread_isvips() );
+}
+
diff --git a/libvips/include/vips/semaphore.h b/libvips/include/vips/semaphore.h
index 8c9ef0fa..75a05f81 100644
--- a/libvips/include/vips/semaphore.h
+++ b/libvips/include/vips/semaphore.h
@@ -58,14 +58,14 @@ typedef struct {
 VIPS_API
 int vips_semaphore_up( VipsSemaphore *s );
 VIPS_API
-int vips_semaphore_down( VipsSemaphore *s );
-VIPS_API
-int vips_semaphore_down_timeout( VipsSemaphore *s, gint64 timeout );
-VIPS_API
 int vips_semaphore_upn( VipsSemaphore *s, int n );
 VIPS_API
+int vips_semaphore_down( VipsSemaphore *s );
+VIPS_API
 int vips_semaphore_downn( VipsSemaphore *s, int n );
 VIPS_API
+int vips_semaphore_down_timeout( VipsSemaphore *s, gint64 timeout );
+VIPS_API
 void vips_semaphore_destroy( VipsSemaphore *s );
 VIPS_API
 void vips_semaphore_init( VipsSemaphore *s, int v, char *name );
diff --git a/libvips/iofuncs/semaphore.c b/libvips/iofuncs/semaphore.c
index 96a67be2..606217e9 100644
--- a/libvips/iofuncs/semaphore.c
+++ b/libvips/iofuncs/semaphore.c
@@ -149,15 +149,18 @@ vips__semaphore_downn_until( VipsSemaphore *s, int n, gint64 end_time )
 	return( value_after_op );
 }
 
-/* Wait for sem>n, then subtract n.
+/* Wait for sem>n, then subtract n. n must be >= 0. Returns the new semaphore
+ * value.
  */
 int
 vips_semaphore_downn( VipsSemaphore *s, int n )
 {
+	g_assert( n >= 0 );
+
 	return( vips__semaphore_downn_until( s, n, -1 ) );
 }
 
-/* Wait for sem > 0, then decrement.
+/* Wait for sem > 0, then decrement. Returns the new semaphore value.
  */
 int
 vips_semaphore_down( VipsSemaphore *s )
@@ -166,8 +169,8 @@ vips_semaphore_down( VipsSemaphore *s )
 }
 
 /* Wait for sem > 0, then decrement.
- * Returns -1 when the relative time in @timeout (in microseconds)
- * was passed.
+ * Returns -1 when @timeout (in microseconds) has passed, or the new 
+ * semaphore value.
  */
 int
 vips_semaphore_down_timeout( VipsSemaphore *s, gint64 timeout )
diff --git a/libvips/iofuncs/thread.c b/libvips/iofuncs/thread.c
index 479e6142..4859538c 100644
--- a/libvips/iofuncs/thread.c
+++ b/libvips/iofuncs/thread.c
@@ -87,14 +87,6 @@ vips_thread_isvips( void )
 	return( g_private_get( is_vips_thread_key ) != NULL );
 }
 
-/* Deprecated compatibility function.
- */
-gboolean
-vips_thread_isworker( void )
-{
-	return( vips_thread_isvips() );
-}
-
 /* Glib 2.32 revised the thread API. We need some compat functions.
  */