diff --git a/api/admin.py b/api/admin.py
index 8a656a19..d2e1f2f1 100644
--- a/api/admin.py
+++ b/api/admin.py
@@ -39,6 +39,9 @@ class ExternalIdentifierAdmin(admin.ModelAdmin):
         "external_id",
         "internal_id",
     ]
+    readonly_fields = [
+        "created",
+    ]
 
 admin.site.register(APIUserToken, APITokenAdmin)
 admin.site.register(OAuthToken, OAuthTokenAdmin)