diff --git a/libvips/iofuncs/memory.c b/libvips/iofuncs/memory.c
index 5868675037..f70a726d30 100644
--- a/libvips/iofuncs/memory.c
+++ b/libvips/iofuncs/memory.c
@@ -262,13 +262,19 @@ vips_tracked_free( void *s )
 	VIPS_GATE_FREE( size ); 
 }
 
+static void
+vips_tracked_init_mutex( void )
+{
+	vips_tracked_mutex = vips_g_mutex_new(); 
+}
+
 static void
 vips_tracked_init( void )
 {
 	static GOnce vips_tracked_once = G_ONCE_INIT;
 
-	vips_tracked_mutex = g_once( &vips_tracked_once, 
-		(GThreadFunc) vips_g_mutex_new, NULL );
+	g_once( &vips_tracked_once, 
+		(GThreadFunc) vips_tracked_init_mutex, NULL );
 }
 
 /**
diff --git a/libvips/iofuncs/object.c b/libvips/iofuncs/object.c
index bb520456e0..b672fda11e 100644
--- a/libvips/iofuncs/object.c
+++ b/libvips/iofuncs/object.c
@@ -2772,20 +2772,20 @@ vips_class_add_hash( VipsObjectClass *class, GHashTable *table )
 	return( NULL ); 
 }
 
-static void *
+static void 
 vips_class_build_hash( void )
 {
-	GHashTable *table;
 	GType base;
 
-	table = g_hash_table_new( g_str_hash, g_str_equal );
+	vips__object_nickname_table = 
+		g_hash_table_new( g_str_hash, g_str_equal );
 
-	if( !(base = g_type_from_name( "VipsObject" )) )
-		return( NULL );
-	vips_class_map_all( base, 
-		(VipsClassMapFn) vips_class_add_hash, (void *) table );
+	base = g_type_from_name( "VipsObject" );
+	g_assert( base ); 
 
-	return( table ); 
+	vips_class_map_all( base, 
+		(VipsClassMapFn) vips_class_add_hash, 
+		(void *) vips__object_nickname_table );
 }
 
 /**
@@ -2814,8 +2814,7 @@ vips_type_find( const char *basename, const char *nickname )
 	GType base;
 	GType type;
 
-	vips__object_nickname_table = (GHashTable *) g_once( &once, 
-		(GThreadFunc) vips_class_build_hash, NULL ); 
+	g_once( &once, (GThreadFunc) vips_class_build_hash, NULL ); 
 
 	hit = (NicknameGType *) 
 		g_hash_table_lookup( vips__object_nickname_table,