diff --git a/shell/view/home/activitiesdonut.py b/shell/view/home/activitiesdonut.py
index 45411da0..950afbd0 100644
--- a/shell/view/home/activitiesdonut.py
+++ b/shell/view/home/activitiesdonut.py
@@ -159,6 +159,7 @@ class ActivityIcon(CanvasIcon):
         if self._pulse_id:
             return
 
+        self.props.cache_size = self._level_max
         self._pulse_id = gobject.timeout_add(self._INTERVAL, self._pulse_cb)
 
     def _stop_pulsing(self):
@@ -167,6 +168,7 @@ class ActivityIcon(CanvasIcon):
 
         self._cleanup()
         self._level = 100.0
+        self.props.cache_size = 1
         self.props.xo_color = self._orig_color
 
     def _resume_activate_cb(self, menuitem):
diff --git a/sugar/graphics/icon.py b/sugar/graphics/icon.py
index b3dc0349..ad57da3e 100644
--- a/sugar/graphics/icon.py
+++ b/sugar/graphics/icon.py
@@ -285,7 +285,7 @@ class _IconBuffer(object):
     def set_cache_size(self, cache_size):
         while len(self._surface_cache) > cache_size:
             self._surface_cache.popitem()
-        self._cache_size
+        self._cache_size = cache_size
 
     cache_size = property(get_cache_size, set_cache_size)