diff --git a/bioimageio/spec/_internal/common_nodes.py b/bioimageio/spec/_internal/common_nodes.py
index 4a258859..09d1a616 100644
--- a/bioimageio/spec/_internal/common_nodes.py
+++ b/bioimageio/spec/_internal/common_nodes.py
@@ -60,6 +60,7 @@
 from .io_utils import write_content_to_zip
 from .node import Node
 from .packaging_context import PackagingContext
+from .root_url import RootHttpUrl
 from .url import HttpUrl
 from .utils import (
     assert_all_params_set_explicitly,
@@ -343,12 +344,12 @@ def validation_summary(self) -> ValidationSummary:
         assert self._validation_summary is not None, "access only after initialization"
         return self._validation_summary
 
-    _root: Union[HttpUrl, DirectoryPath] = PrivateAttr(
+    _root: Union[RootHttpUrl, DirectoryPath, ZipPath] = PrivateAttr(
         default_factory=lambda: validation_context_var.get().root
     )
 
     @property
-    def root(self) -> Union[HttpUrl, DirectoryPath]:
+    def root(self) -> Union[RootHttpUrl, DirectoryPath, ZipPath]:
         return self._root
 
     @classmethod
diff --git a/bioimageio/spec/_internal/url.py b/bioimageio/spec/_internal/url.py
index 2865439a..de998d96 100644
--- a/bioimageio/spec/_internal/url.py
+++ b/bioimageio/spec/_internal/url.py
@@ -121,7 +121,7 @@ class HttpUrl(RootHttpUrl):
     _exists: Optional[bool] = None
 
     def _after_validator(self):
-        super()._after_validator()
+        self = super()._after_validator()
         context = validation_context_var.get()
         if (
             context.perform_io_checks
diff --git a/bioimageio/spec/_internal/validation_context.py b/bioimageio/spec/_internal/validation_context.py
index 7195c0b7..43caa206 100644
--- a/bioimageio/spec/_internal/validation_context.py
+++ b/bioimageio/spec/_internal/validation_context.py
@@ -10,7 +10,7 @@
 from pydantic import DirectoryPath
 
 from ._settings import settings
-from .io_basics import AbsoluteDirectory, FileName, Sha256
+from .io_basics import FileName, Sha256
 from .root_url import RootHttpUrl
 from .warning_levels import WarningLevel
 
@@ -21,7 +21,7 @@ class ValidationContext:
         init=False, default_factory=list
     )
 
-    root: Union[RootHttpUrl, AbsoluteDirectory, ZipFile] = Path()
+    root: Union[RootHttpUrl, DirectoryPath, ZipFile] = Path()
     """url/directory serving as base to resolve any relative file paths"""
 
     warning_level: WarningLevel = 50
diff --git a/tests/test_internal/test_url.py b/tests/test_internal/test_url.py
index aecd8f14..73f3027d 100644
--- a/tests/test_internal/test_url.py
+++ b/tests/test_internal/test_url.py
@@ -2,6 +2,7 @@
 
 import pytest
 import requests.exceptions
+from requests_mock import Mocker as RequestsMocker
 
 from bioimageio.spec._internal.validation_context import ValidationContext
 
@@ -32,11 +33,11 @@ def test_httpurl_valid(url: str):
         ("let's ignore this I guess??", 405),
     ],
 )
-def test_httpurl_mock_valid(text: str, status_code: int, requests_mock):
+def test_httpurl_mock_valid(text: str, status_code: int, requests_mock: RequestsMocker):
     from bioimageio.spec._internal.url import HttpUrl
 
     url = "https://example.com"
-    requests_mock.get(url, text=text, status_code=status_code)
+    _ = requests_mock.get(url, text=text, status_code=status_code)
     assert HttpUrl(url).exists()
 
 
@@ -48,12 +49,14 @@ def test_httpurl_mock_valid(text: str, status_code: int, requests_mock):
         ("just wrong", 199),
     ],
 )
-def test_httpurl_mock_invalid(text: str, status_code: int, requests_mock):
+def test_httpurl_mock_invalid(
+    text: str, status_code: int, requests_mock: RequestsMocker
+):
     from bioimageio.spec._internal.url import HttpUrl
 
     url = "https://example.com"
-    requests_mock.head(url, text=text, status_code=status_code)
-    requests_mock.get(url, text=text, status_code=status_code)
+    _ = requests_mock.head(url, text=text, status_code=status_code)
+    _ = requests_mock.get(url, text=text, status_code=status_code)
     with ValidationContext(perform_io_checks=True):
         with pytest.raises(ValueError):
             _ = HttpUrl(url)
@@ -68,11 +71,11 @@ def test_httpurl_mock_invalid(text: str, status_code: int, requests_mock):
         requests.exceptions.InvalidURL,
     ],
 )
-def test_httpurl_mock_exc(exc: Type[Exception], requests_mock):
+def test_httpurl_mock_exc(exc: Type[Exception], requests_mock: RequestsMocker):
     from bioimageio.spec._internal.url import HttpUrl
 
     url = "https://example.com"
-    requests_mock.head(url, exc=exc)
+    _ = requests_mock.head(url, exc=exc)
     with ValidationContext(perform_io_checks=True):
         with pytest.raises(ValueError):
             _ = HttpUrl(url)