diff --git a/django/contrib/admin/widgets.py b/django/contrib/admin/widgets.py
index 99bfdef53d..7ce0d36023 100644
--- a/django/contrib/admin/widgets.py
+++ b/django/contrib/admin/widgets.py
@@ -98,8 +98,8 @@ class ManyToManyRawIdWidget(ForeignKeyRawIdWidget):
     
     def render(self, name, value, attrs=None):
         attrs['class'] = 'vManyToManyRawIdAdminField'
-        if value: 
-            value = ','.join(value)
+        if value:
+            value = ','.join([str(v) for v in value])
         else: 
             value = ""
         return super(ManyToManyRawIdWidget, self).render(name, value, attrs)