diff --git a/beets/library.py b/beets/library.py
index 3a120b720..9a921b9a6 100644
--- a/beets/library.py
+++ b/beets/library.py
@@ -121,8 +121,10 @@ class Item(object):
         Otherwise, performs an ordinary setattr."""
         
         if key in item_keys:
-            self.record[key] = value
-            self.dirty[key] = True
+            if (not (key in self.record)) or (self.record[key] != value):
+                # don't dirty if value unchanged
+                self.record[key] = value
+                self.dirty[key] = True
         else:
             object.__setattr__(self, key, value)
     
diff --git a/test/test_db.py b/test/test_db.py
index 07f5eeed9..ad3076d48 100755
--- a/test/test_db.py
+++ b/test/test_db.py
@@ -117,8 +117,12 @@ class GetSetTest(unittest.TestCase):
         self.assertEqual(self.i.bpm, 4915)
     
     def test_set_sets_dirty_flag(self):
-        self.i.comp = True
+        self.i.comp = not self.i.comp
         self.assertTrue(self.i.dirty['comp'])
+    
+    def test_set_does_not_dirty_if_value_unchanged(self):
+        self.i.title = self.i.title
+        self.assertTrue(not self.i.dirty['title'])
 
 class DestinationTest(unittest.TestCase):
     def setUp(self):