diff --git a/picard/collection.py b/picard/collection.py
index 11ba17660..a983a2156 100644
--- a/picard/collection.py
+++ b/picard/collection.py
@@ -30,6 +30,8 @@ user_collections = {}
 
 
 class Collection(QtCore.QObject):
+    COLLECTION_ADD = 1
+    COLLECTION_REMOVE = 2
 
     def __init__(self, collection_id, name, size):
         self.id = collection_id
@@ -37,66 +39,52 @@ class Collection(QtCore.QObject):
         self.pending = set()
         self.size = int(size)
         self.releases = set()
+        mb_api = self.tagger.mb_api
+        self.api_action = {
+            self.COLLECTION_ADD: mb_api.put_to_collection,
+            self.COLLECTION_REMOVE: mb_api.delete_from_collection,
+        }
 
     def __repr__(self):
         return '<Collection %s (%s)>' % (self.name, self.id)
 
-    def add_releases(self, ids, callback):
-        ids = ids - self.pending
+    def _modify(self, kind, ids, callback):
+        ids -= self.pending
         if ids:
-            self.pending.update(ids)
-            self.tagger.mb_api.put_to_collection(self.id, list(ids),
-                partial(self._add_finished, ids, callback))
+            self.pending |= ids
+            when_done = partial(self._finished, kind, ids, callback)
+            self.api_action[kind](self.id, list(ids), when_done)
+
+    def add_releases(self, ids, callback):
+        self._modify(self.COLLECTION_ADD, ids, callback)
 
     def remove_releases(self, ids, callback):
-        ids = ids - self.pending
-        if ids:
-            self.pending.update(ids)
-            self.tagger.mb_api.delete_from_collection(self.id, list(ids),
-                partial(self._remove_finished, ids, callback))
+        self._modify(self.COLLECTION_REMOVE, ids, callback)
 
-    def _add_finished(self, ids, callback, document, reply, error):
-        self.pending.difference_update(ids)
+    def _finished(self, kind, ids, callback, document, reply, error):
+        self.pending -= ids
         if not error:
             count = len(ids)
-            self.releases.update(ids)
-            self.size += count
+            if kind == self.COLLECTION_ADD:
+                self.releases |= ids
+                self.size += count
+                status_msg = ngettext(
+                    'Added %(count)i release to collection "%(name)s"',
+                    'Added %(count)i releases to collection "%(name)s"',
+                    count)
+                debug_msg = 'Added %(count)i releases to collection "%(name)s"'
+            else:
+                self.releases -= ids
+                self.size -= count
+                status_msg = ngettext(
+                    'Removed %(count)i release from collection "%(name)s"',
+                    'Removed %(count)i releases from collection "%(name)s"',
+                    count)
+                debug_msg = 'Removed %(count)i releases from collection "%(name)s"'
             callback()
-            mparms = {
-                'count': count,
-                'name': self.name
-            }
-            log.debug('Added %(count)i releases to collection "%(name)s"' % mparms)
-            self.tagger.window.set_statusbar_message(
-                ngettext('Added %(count)i release to collection "%(name)s"',
-                         'Added %(count)i releases to collection "%(name)s"',
-                         count),
-                mparms,
-                translate=None,
-                echo=None
-            )
-
-    def _remove_finished(self, ids, callback, document, reply, error):
-        self.pending.difference_update(ids)
-        if not error:
-            count = len(ids)
-            self.releases.difference_update(ids)
-            self.size -= count
-            callback()
-            mparms = {
-                'count': count,
-                'name': self.name
-            }
-            log.debug('Removed %(count)i releases from collection "%(name)s"' %
-                      mparms)
-            self.tagger.window.set_statusbar_message(
-                ngettext('Removed %(count)i release from collection "%(name)s"',
-                         'Removed %(count)i releases from collection "%(name)s"',
-                         count),
-                mparms,
-                translate=None,
-                echo=None
-            )
+            mparms = {'count': count, 'name': self.name}
+            log.debug(debug_msg % mparms)
+            self.tagger.window.set_statusbar_message(status_msg, mparms, translate=None, echo=None)
 
 
 def load_user_collections(callback=None):