diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 279ca941..845fa8a8 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -23,6 +23,8 @@ Fixed
   <https://github.com/omni-us/jsonargparse/pull/728>`__).
 - ArgumentParser with dashes incorrectly resolves paths to default values (`#736
   <https://github.com/omni-us/jsonargparse/pull/736>`__).
+- Fix failing tests due to new version of ``typeshed-client`` (`#740
+  <https://github.com/omni-us/jsonargparse/pull/740>`__).
 
 
 v4.40.0 (2025-05-16)
diff --git a/jsonargparse/_stubs_resolver.py b/jsonargparse/_stubs_resolver.py
index 2405a0b9..4d26d928 100644
--- a/jsonargparse/_stubs_resolver.py
+++ b/jsonargparse/_stubs_resolver.py
@@ -157,11 +157,9 @@ def get_component_imported_info(self, component, parent) -> Optional[tc.Imported
         stub_import = parent and self.get_imported_info(f"{parent.__module__}.{parent.__name__}", component)
         if stub_import and isinstance(stub_import.info.ast, ast.AST):
             method_ast = MethodsVisitor().find(stub_import.info.ast, component.__name__)
-            if method_ast is None:
-                stub_import = None
-            else:
-                name_info = tc.NameInfo(name=component.__qualname__, is_exported=False, ast=method_ast)
-                stub_import = tc.ImportedInfo(source_module=stub_import.source_module, info=name_info)
+            assert method_ast
+            name_info = tc.NameInfo(name=component.__qualname__, is_exported=False, ast=method_ast)
+            stub_import = tc.ImportedInfo(source_module=stub_import.source_module, info=name_info)
         return stub_import
 
     def get_aliases(self, imported_info: tc.ImportedInfo):
diff --git a/jsonargparse_tests/test_stubs_resolver.py b/jsonargparse_tests/test_stubs_resolver.py
index 0f30399e..3a2bb4f0 100644
--- a/jsonargparse_tests/test_stubs_resolver.py
+++ b/jsonargparse_tests/test_stubs_resolver.py
@@ -144,9 +144,9 @@ def test_get_params_conditional_python_version():
     assert [("a", inspect._empty), ("version", inspect._empty)] == get_param_types(params)
 
 
-@patch("jsonargparse._stubs_resolver.exec")
-def test_get_params_exec_failure(mock_exec):
-    mock_exec.side_effect = NameError("failed")
+@patch("jsonargparse._parameter_resolvers.get_stub_types")
+def test_get_params_exec_failure(mock_get_stub_types):
+    mock_get_stub_types.return_value = None
     params = get_params(Random, "seed")
     assert [("a", inspect._empty), ("version", inspect._empty)] == get_param_types(params)
 
@@ -172,7 +172,9 @@ def test_get_params_classmethod():
         expected = expected[:4] + ["compresslevel"] + expected[4:]
     assert expected == get_param_names(params)[: len(expected)]
     if sys.version_info >= (3, 10):
-        assert all(p.annotation is not inspect._empty for p in params if p.name not in {"compresslevel", "stream"})
+        assert all(
+            p.annotation is not inspect._empty for p in params if p.name not in {"fileobj", "compresslevel", "stream"}
+        )
     with mock_stubs_missing_types():
         params = get_params(TarFile, "open")
     assert expected == get_param_names(params)[: len(expected)]
diff --git a/pyproject.toml b/pyproject.toml
index 3e5415bf..b05358fd 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -52,7 +52,8 @@ all = [
 signatures = [
     "jsonargparse[typing-extensions]",
     "docstring-parser>=0.15",
-    "typeshed-client>=2.3.0",
+    "typeshed-client>=2.3.0; python_version == '3.8'",
+    "typeshed-client>=2.8.2; python_version >= '3.9'",
 ]
 jsonschema = [
     "jsonschema>=3.2.0",