diff --git a/fkreplace/__init__.py b/fkreplace/__init__.py
index e8ded47..5007f91 100644
--- a/fkreplace/__init__.py
+++ b/fkreplace/__init__.py
@@ -17,9 +17,12 @@ def merge(from_obj, to_obj):
             import pdb; pdb.set_trace()
             raise Exception('unknown code path')
 
-    for related_m2m in from_obj._meta.get_all_related_many_to_many_objects():
+    for related in from_obj._meta.get_all_related_many_to_many_objects():
         accessor_name = related.get_accessor_name()
-        varname = related.field.name
-
-        #for obj in getattr(from_obj, varname)
-
+        if accessor_name:
+            varname = related.field.name
+            field = getattr(from_obj, accessor_name)
+            if related.many_to_many:
+                for f in field.all():
+                    getattr(f, varname).remove(from_obj)
+                    getattr(f, varname).add(to_obj)
diff --git a/tests/models.py b/tests/models.py
index 1aa860c..4d589f0 100644
--- a/tests/models.py
+++ b/tests/models.py
@@ -18,4 +18,4 @@ class SSN(models.Model):
 
 class Group(models.Model):
     name = models.CharField(max_length=100)
-    people = models.ManyToManyField(Person)
+    people = models.ManyToManyField(Person, related_name='groups')
diff --git a/tests/tests.py b/tests/tests.py
index fdd428a..17183a8 100644
--- a/tests/tests.py
+++ b/tests/tests.py
@@ -37,3 +37,27 @@ class MergeTests(TestCase):
         c = Person.objects.get(pk=self.c.pk)
         c.ssn.number == 1
         assert SSN.objects.count() == 2
+
+    # TODO: test one2one when there's a conflict
+
+    def test_many2many_simple(self):
+        merge(self.a, self.c)
+        # A's membership in G has been moved to C
+        assert self.g.people.all().count() == 2
+        assert self.a.groups.all().count() == 0
+        assert self.c.groups.all().count() == 1
+
+    def test_many2many_redundant(self):
+        merge(self.a, self.b)
+        # A's membership in G is redundant with B's
+        assert self.g.people.all().count() == 1
+        assert self.a.groups.all().count() == 0
+        assert self.b.groups.all().count() == 1
+
+    def test_many2many_self(self):
+        self.a.friends.add(self.b)
+        merge(self.a, self.c)
+        import pdb; pdb.set_trace()
+        assert self.a.friends.all().count() == 0
+        assert self.b.friends.get().name == self.c
+        assert self.c.friends.get().name == self.b