diff --git a/examples/__globals__.py b/examples/__globals__.py
index 9893ba9..afce5cd 100644
--- a/examples/__globals__.py
+++ b/examples/__globals__.py
@@ -26,7 +26,8 @@ async def _on_request(self, **server):
     async def _on_response(self, **server):
         response = server['response']
 
-        del response.headers[b'x-debug']
+        if not response.headers_sent():
+            del response.headers[b'x-debug']
 
 
 app.logger.info('entering %s', __file__)
diff --git a/httpout/httpout.py b/httpout/httpout.py
index bade490..63d71a4 100644
--- a/httpout/httpout.py
+++ b/httpout/httpout.py
@@ -231,11 +231,6 @@ async def _on_request(self, **server):
             else:
                 server['websocket'] = None
 
-            excludes = (server['response'].print,
-                        server['response'].run_coroutine,
-                        g.wait,
-                        *server.values())
-
             server['REQUEST_METHOD'] = request.method.decode('latin-1')
             server['SCRIPT_NAME'] = module_path[len(document_root):].replace(
                 os.sep, '/'
@@ -278,7 +273,7 @@ async def _on_request(self, **server):
                 await server['response'].handle_exception(exc)
             finally:
                 await g.executor.submit(
-                    cleanup_modules, server['modules'], excludes
+                    cleanup_modules, server['modules'], g.options['debug']
                 )
                 await server['response'].join()
                 server['modules'].clear()
diff --git a/httpout/utils/modules.py b/httpout/utils/modules.py
index d0e1696..fd74768 100644
--- a/httpout/utils/modules.py
+++ b/httpout/utils/modules.py
@@ -1,6 +1,7 @@
 # Copyright (c) 2024 nggit
 
 import os
+import sys
 
 from types import ModuleType
 
@@ -19,13 +20,24 @@ def exec_module(module, code=None, max_size=8 * 1048576):
     exec(code, module.__dict__)  # nosec B102
 
 
-def cleanup_modules(modules, excludes=()):
+def cleanup_modules(modules, debug=0):
+    if debug:
+        if debug == 1:
+            print('  cleanup_modules:')
+
+        debug += 4
+
     for module_name, module in modules.items():
         module_dict = getattr(module, '__dict__', None)
 
         if module_dict:
             for name, value in module_dict.items():
-                if value in excludes or name.startswith('__'):
+                if name.startswith('__'):
+                    continue
+
+                value_module = getattr(value, '__module__', '__main__')
+
+                if value_module != '__main__' and value_module in sys.modules:
                     continue
 
                 if not (value is module or
@@ -33,9 +45,16 @@ def cleanup_modules(modules, excludes=()):
                     value_dict = getattr(value, '__dict__', None)
 
                     if value_dict:
-                        cleanup_modules(value_dict, excludes)
+                        cleanup_modules(value_dict, debug)
 
                 module_dict[name] = None
 
+                if debug:
+                    print(' ' * debug, ',-- deleted:', name, value)
+
         if not module_name.startswith('__'):
             modules[module_name] = None
+
+            if debug:
+                print(' ' * debug, '|')
+                print(' ' * debug, 'deleted:', module_name, module)
diff --git a/httpout/utils/modules.pyx b/httpout/utils/modules.pyx
index b2b0198..32fcb5f 100644
--- a/httpout/utils/modules.pyx
+++ b/httpout/utils/modules.pyx
@@ -1,5 +1,7 @@
 # Copyright (c) 2024 nggit
 
+import sys
+
 from types import ModuleType
 
 from libc.stdio cimport (FILE, fopen, fclose, fread, feof, ferror,
@@ -50,16 +52,27 @@ def exec_module(module, code=None, size_t max_size=8 * 1048576):
     exec(code, module.__dict__)
 
 
-def cleanup_modules(modules, tuple excludes=()):
+def cleanup_modules(modules, int debug=0):
     cdef str module_name, name
     cdef dict module_dict, value_dict
 
+    if debug:
+        if debug == 1:
+            print('  cleanup_modules:')
+
+        debug += 4
+
     for module_name, module in modules.items():
         module_dict = getattr(module, '__dict__', None)
 
         if module_dict:
             for name, value in module_dict.items():
-                if value in excludes or name.startswith('__'):
+                if name.startswith('__'):
+                    continue
+
+                value_module = getattr(value, '__module__', '__main__')
+
+                if value_module != '__main__' and value_module in sys.modules:
                     continue
 
                 if not (value is module or
@@ -67,9 +80,16 @@ def cleanup_modules(modules, tuple excludes=()):
                     value_dict = getattr(value, '__dict__', None)
 
                     if value_dict:
-                        cleanup_modules(value_dict, excludes)
+                        cleanup_modules(value_dict, debug)
 
                 module_dict[name] = None
 
+                if debug:
+                    print(' ' * debug, ',-- deleted:', name, value)
+
         if not module_name.startswith('__'):
             modules[module_name] = None
+
+            if debug:
+                print(' ' * debug, '|')
+                print(' ' * debug, 'deleted:', module_name, module)