diff --git a/python_jsonschema_objects/classbuilder.py b/python_jsonschema_objects/classbuilder.py
index b230977..94a8396 100644
--- a/python_jsonschema_objects/classbuilder.py
+++ b/python_jsonschema_objects/classbuilder.py
@@ -276,7 +276,7 @@ class ProtocolBase(collections.MutableMapping):
             prop.__delete__(self)
             return
 
-        return delattr(self, name)
+        return object.__delattr__(self, name)
 
     @classmethod
     def propinfo(cls, propname):

Infinite recursion when deleting internal attribute
The recent fix of #165 introduced a new bug, unfortunately.
The function `ProtocolBase.__delattr__` calls `delattr` again, if the two conditions don't match. This causes an infinite recursion when trying to delete an internal attribute, or one that does not exist:
```
>>> test = namespace.Test()
>>> delattr(test, 'foo')
…
RecursionError: maximum recursion depth exceeded
```
Instead of calling `delattr`, the function should call `object.__delattr__` to avoid this problem (similar to what `__setattr__` does).
diff --git a/test/test_regression_165.py b/test/test_regression_165.py
index 0b5fd97..d785714 100644
--- a/test/test_regression_165.py
+++ b/test/test_regression_165.py
@@ -10,8 +10,11 @@ def testclass():
 
 
 def test_extra_properties_can_be_deleted_with_item_syntax(testclass):
-    testclass.foo = 42
+    # Deletion before setting should throw attribute errors
+    with pytest.raises(AttributeError):
+        del testclass["foo"]
 
+    testclass.foo = 42
     assert testclass.foo == 42
     del testclass["foo"]
 
@@ -21,8 +24,11 @@ def test_extra_properties_can_be_deleted_with_item_syntax(testclass):
 
 
 def test_extra_properties_can_be_deleted_with_attribute_syntax(testclass):
-    testclass.foo = 42
+    # Deletion before setting should throw attribute errors
+    with pytest.raises(AttributeError):
+        del testclass.foo
 
+    testclass.foo = 42
     assert testclass.foo == 42
     del testclass.foo
 
@@ -32,8 +38,11 @@ def test_extra_properties_can_be_deleted_with_attribute_syntax(testclass):
 
 
 def test_extra_properties_can_be_deleted_directly(testclass):
-    testclass.foo = 42
+    # Deletion before setting should throw attribute errors
+    with pytest.raises(AttributeError):
+        delattr(testclass, "foo")
 
+    testclass.foo = 42
     assert testclass.foo == 42
     delattr(testclass, "foo")
 
@@ -42,9 +51,37 @@ def test_extra_properties_can_be_deleted_directly(testclass):
         testclass.foo
 
 
-def test_real_properties_arent_really_deleted(Person):
+def test_unrequired_real_properties_arent_really_deleted(Person):
     p = Person(age=20)
 
     assert p.age == 20
     del p.age
     assert p.age == None
+
+    p.age = 20
+    assert p.age == 20
+    delattr(p, "age")
+    assert p.age == None
+
+    p.age = 20
+    assert p.age == 20
+    del p["age"]
+    assert p.age == None
+
+
+def test_required_real_properties_throw_attributeerror_on_delete(Person):
+    p = Person(firstName="Fred")
+
+    assert p.firstName == "Fred"
+    with pytest.raises(AttributeError):
+        del p.firstName
+
+    p.firstName = "Fred"
+    assert p.firstName == "Fred"
+    with pytest.raises(AttributeError):
+        delattr(p, "firstName")
+
+    p.firstName = "Fred"
+    assert p.firstName == "Fred"
+    with pytest.raises(AttributeError):
+        del p["firstName"]

pip install -e .
parse_log_pytest
requirements.txt
pytest pytest-mock
3.6
development.txt
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
alabaster==0.7.13
attrs==22.2.0
Babel==2.11.0
certifi==2021.5.30
charset-normalizer==2.0.12
colorama==0.4.5
commonmark==0.9.1
docutils==0.18.1
idna==3.10
imagesize==1.4.1
importlib-metadata==4.8.3
inflection==0.5.1
iniconfig==1.1.1
Jinja2==3.0.3
jsonschema==3.2.0
livereload==2.6.3
Markdown==3.3.7
MarkupSafe==2.0.1
nose==1.3.0
packaging==21.3
pandoc==2.4
pluggy==1.0.0
plumbum==1.8.3
ply==3.11
py==1.11.0
pyandoc==0.2.0
Pygments==2.14.0
pyparsing==3.1.4
pyrsistent==0.18.0
pytest==7.0.1
pytest-mock==3.6.1
-e git+https://github.com/cwacek/python-jsonschema-objects.git@773f4be636fae50432d230fb6b7dad744d257bcc#egg=python_jsonschema_objects
python-termstyle==0.1.10
pytz==2025.2
recommonmark==0.7.1
rednose==0.4.1
requests==2.27.1
six==1.17.0
snowballstemmer==2.2.0
Sphinx==5.3.0
sphinx-autobuild==2021.3.14
sphinxcontrib-applehelp==1.0.2
sphinxcontrib-devhelp==1.0.2
sphinxcontrib-htmlhelp==2.0.0
sphinxcontrib-jsmath==1.0.1
sphinxcontrib-qthelp==1.0.3
sphinxcontrib-serializinghtml==1.1.5
tomli==1.2.3
tornado==6.1
typing_extensions==4.1.1
urllib3==1.26.20
zipp==3.6.0

name: python-jsonschema-objects
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - ca-certificates=2025.2.25=h06a4308_0
  - certifi=2021.5.30=py36h06a4308_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.3=he6710b0_2
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - ncurses=6.4=h6a678d5_0
  - openssl=1.1.1w=h7f8727e_0
  - pip=21.2.2=py36h06a4308_0
  - python=3.6.13=h12debd9_1
  - readline=8.2=h5eee18b_0
  - setuptools=58.0.4=py36h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - wheel=0.37.1=pyhd3eb1b0_0
  - xz=5.6.4=h5eee18b_1
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - alabaster==0.7.13
      - attrs==22.2.0
      - babel==2.11.0
      - charset-normalizer==2.0.12
      - colorama==0.4.5
      - commonmark==0.9.1
      - docutils==0.18.1
      - idna==3.10
      - imagesize==1.4.1
      - importlib-metadata==4.8.3
      - inflection==0.5.1
      - iniconfig==1.1.1
      - jinja2==3.0.3
      - jsonschema==3.2.0
      - livereload==2.6.3
      - markdown==3.3.7
      - markupsafe==2.0.1
      - nose==1.3.0
      - packaging==21.3
      - pandoc==2.4
      - pluggy==1.0.0
      - plumbum==1.8.3
      - ply==3.11
      - py==1.11.0
      - pyandoc==0.2.0
      - pygments==2.14.0
      - pyparsing==3.1.4
      - pyrsistent==0.18.0
      - pytest==7.0.1
      - pytest-mock==3.6.1
      - python-termstyle==0.1.10
      - pytz==2025.2
      - recommonmark==0.7.1
      - rednose==0.4.1
      - requests==2.27.1
      - six==1.17.0
      - snowballstemmer==2.2.0
      - sphinx==5.3.0
      - sphinx-autobuild==2021.3.14
      - sphinxcontrib-applehelp==1.0.2
      - sphinxcontrib-devhelp==1.0.2
      - sphinxcontrib-htmlhelp==2.0.0
      - sphinxcontrib-jsmath==1.0.1
      - sphinxcontrib-qthelp==1.0.3
      - sphinxcontrib-serializinghtml==1.1.5
      - tomli==1.2.3
      - tornado==6.1
      - typing-extensions==4.1.1
      - urllib3==1.26.20
      - zipp==3.6.0
prefix: /opt/conda/envs/python-jsonschema-objects

test/test_regression_165.py::test_extra_properties_can_be_deleted_with_item_syntax test/test_regression_165.py::test_extra_properties_can_be_deleted_with_attribute_syntax test/test_regression_165.py::test_extra_properties_can_be_deleted_directly
test/test_regression_165.py::test_unrequired_real_properties_arent_really_deleted test/test_regression_165.py::test_required_real_properties_throw_attributeerror_on_delete
python_jsonschema_objects/classbuilder.py
python_jsonschema_objects/classbuilder.py