diff --git a/photologue/admin.py b/photologue/admin.py
index a250d38..11b49cc 100644
--- a/photologue/admin.py
+++ b/photologue/admin.py
@@ -144,7 +144,7 @@ class PhotoAdmin(admin.ModelAdmin):
     search_fields = ['title', 'slug', 'caption']
     list_per_page = 10
     prepopulated_fields = {'slug': ('title',)}
-    readonly_fields = ('date_taken',)
+    readonly_fields = ('date_taken', 'admin_thumbnail')
     form = PhotoAdminForm
     if MULTISITE:
         filter_horizontal = ['sites']