diff --git a/src/libsysprof-ui/pointcache.c b/src/libsysprof-ui/pointcache.c
index 8072ac14..c16304ff 100644
--- a/src/libsysprof-ui/pointcache.c
+++ b/src/libsysprof-ui/pointcache.c
@@ -24,25 +24,36 @@
 
 struct _PointCache
 {
-  GHashTable *sets;
+  volatile gint  ref_count;
+  GHashTable    *sets;
 };
 
 static void
-point_cache_clear (PointCache *self)
+point_cache_finalize (PointCache *self)
 {
   g_clear_pointer (&self->sets, g_hash_table_unref);
+  g_slice_free (PointCache, self);
 }
 
 PointCache *
 point_cache_ref (PointCache *self)
 {
-  return g_atomic_rc_box_acquire (self);
+  g_return_val_if_fail (self != NULL, NULL);
+  g_return_val_if_fail (self->ref_count > 0, NULL);
+
+  g_atomic_int_inc (&self->ref_count);
+
+  return self;
 }
 
 void
 point_cache_unref (PointCache *self)
 {
-  g_atomic_rc_box_release_full (self, (GDestroyNotify) point_cache_clear);
+  g_return_if_fail (self != NULL);
+  g_return_if_fail (self->ref_count > 0);
+
+  if (g_atomic_int_dec_and_test (&self->ref_count))
+    point_cache_finalize (self);
 }
 
 PointCache *
@@ -50,7 +61,8 @@ point_cache_new (void)
 {
   PointCache *self;
 
-  self = g_atomic_rc_box_new0 (PointCache);
+  self = g_slice_new0 (PointCache);
+  self->ref_count = 1;
   self->sets = g_hash_table_new_full (NULL, NULL, NULL, (GDestroyNotify)g_array_unref);
 
   return self;
diff --git a/src/libsysprof-ui/sysprof-depth-visualizer.c b/src/libsysprof-ui/sysprof-depth-visualizer.c
index 39ebf37d..118489d7 100644
--- a/src/libsysprof-ui/sysprof-depth-visualizer.c
+++ b/src/libsysprof-ui/sysprof-depth-visualizer.c
@@ -55,16 +55,11 @@ static void sysprof_depth_visualizer_reload (SysprofDepthVisualizer *self);
 G_DEFINE_TYPE (SysprofDepthVisualizer, sysprof_depth_visualizer, SYSPROF_TYPE_VISUALIZER)
 
 static void
-state_clear (State *st)
+state_free (State *st)
 {
   g_clear_pointer (&st->reader, sysprof_capture_reader_unref);
   g_clear_pointer (&st->pc, point_cache_unref);
-}
-
-static void
-state_unref (State *st)
-{
-  g_atomic_rc_box_release_full (st, (GDestroyNotify) state_clear);
+  g_slice_free (State, st);
 }
 
 static gboolean
@@ -201,7 +196,7 @@ sysprof_depth_visualizer_reload (SysprofDepthVisualizer *self)
 
   gtk_widget_get_allocation (GTK_WIDGET (self), &alloc);
 
-  st = g_atomic_rc_box_new0 (State);
+  st = g_slice_new0 (State);
   st->reader = sysprof_capture_reader_ref (self->reader);
   st->pc = point_cache_new ();
   st->max_n_addrs = 0;
@@ -215,7 +210,7 @@ sysprof_depth_visualizer_reload (SysprofDepthVisualizer *self)
 
   task = g_task_new (self, NULL, apply_point_cache_cb, NULL);
   g_task_set_source_tag (task, sysprof_depth_visualizer_reload);
-  g_task_set_task_data (task, st, (GDestroyNotify) state_unref);
+  g_task_set_task_data (task, st, (GDestroyNotify) state_free);
   g_task_run_in_thread (task, sysprof_depth_visualizer_worker);
 }