diff --git a/README.rst b/README.rst
index c447554..41f90a6 100644
--- a/README.rst
+++ b/README.rst
@@ -98,6 +98,20 @@ Django will silently throw away `hello!` because you wrote :code:`contents` inst
 of :code:`content`. :code:`django-fastdev` will turn this into an error which lists the
 invalid and valid block names in alphabetical order.
 
+You can customize the filter to understand also custom blocks in your `settings.py` file in this way (an example to integrate [Unfold](https://github.com/unfoldadmin/django-unfold)):
+
+settings.py:
+
+```
+FASTDEV_INVALID_BLOCKS_CALLBACK = "your_app.settings.fastdev_blocks"
+
+def fastdev_blocks(x, result):
+    if hasattr(x, 'varname') and x.varname is not None:
+        result.add(x.varname)
+        result.add(x.varname.replace('_', '-'))
+    return result
+```
+
 Better error messages for reverse
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/django_fastdev/apps.py b/django_fastdev/apps.py
index 6aa682d..2118b0f 100644
--- a/django_fastdev/apps.py
+++ b/django_fastdev/apps.py
@@ -4,6 +4,7 @@
 import subprocess
 import sys
 import threading
+import importlib
 from functools import cache
 from typing import Optional
 import warnings
@@ -450,6 +451,10 @@ def get_extends_node_parent(extends_node, context):
         def collect_valid_blocks(template, context):
             result = set()
             for x in template.nodelist:
+                if getattr(settings, 'FASTDEV_INVALID_BLOCKS_CALLBACK', False) is not False:
+                    module, callback = settings.FASTDEV_INVALID_BLOCKS_CALLBACK.rsplit(".", 1)
+                    module = importlib.import_module(module)
+                    result = getattr(module, callback)(x, result)
                 if isinstance(x, ExtendsNode):
                     result |= collect_nested_blocks(x)
                     result |= collect_valid_blocks(get_extends_node_parent(x, context), context)