diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index c4d2a7e..b1ee66d 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -23,7 +23,7 @@ repos:
     hooks:
       - id: pyproject-fmt
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: "v0.15.13"
+    rev: "v0.15.14"
     hooks:
       - id: ruff-format
       - id: ruff
diff --git a/src/pyproject_api/_backend.py b/src/pyproject_api/_backend.py
index cf51d77..96a50f5 100644
--- a/src/pyproject_api/_backend.py
+++ b/src/pyproject_api/_backend.py
@@ -90,8 +90,7 @@ def run(argv):  # noqa: C901, PLR0912, PLR0915
             try:
                 cmd = parsed_message["cmd"]
                 print("Backend: run command {} with args {}".format(cmd, parsed_message["kwargs"]))
-                outcome = backend_proxy(parsed_message["cmd"], **parsed_message["kwargs"])
-                result["return"] = outcome
+                result["return"] = backend_proxy(cmd, **parsed_message["kwargs"])
                 if cmd == "_exit":
                     break
             except BaseException as exception:  # noqa: BLE001
diff --git a/tests/demo_pkg_inline/build.py b/tests/demo_pkg_inline/build.py
index cc0ba5c..afd9318 100644
--- a/tests/demo_pkg_inline/build.py
+++ b/tests/demo_pkg_inline/build.py
@@ -99,7 +99,7 @@ def get_requires_for_build_sdist(config_settings: dict[str, str] | None = None)
 if "HAS_REQUIRES_EDITABLE" in os.environ:
 
     def get_requires_for_build_editable(config_settings: dict[str, str] | None = None) -> list[str]:  # noqa: ARG001
-        return [1] if "REQUIRES_EDITABLE_BAD_RETURN" in os.environ else ["editables"]  # type: ignore[list-item]
+        return [1] if "REQUIRES_EDITABLE_BAD_RETURN" in os.environ else ["editables"]  # type: ignore[invalid-return-type]
 
 
 if "HAS_PREPARE_EDITABLE" in os.environ:
@@ -114,7 +114,7 @@ def prepare_metadata_for_build_editable(
             (dest.parent / arc_name).write_text(dedent(data).strip())
         print(f"created metadata {dest}")  # noqa: T201
         if "PREPARE_EDITABLE_BAD" in os.environ:
-            return 1  # type: ignore[return-value] # checking bad type on purpose
+            return 1  # type: ignore[invalid-return-type] # checking bad type on purpose
         return dist_info
 
 
@@ -124,5 +124,5 @@ def build_editable(
     config_settings: dict[str, str] | None = None,
 ) -> str:
     if "BUILD_EDITABLE_BAD" in os.environ:
-        return 1  # type: ignore[return-value] # checking bad type on purpose
+        return 1  # type: ignore[invalid-return-type] # checking bad type on purpose
     return build_wheel(wheel_directory, metadata_directory, config_settings)
diff --git a/tests/test_frontend_setuptools.py b/tests/test_frontend_setuptools.py
index 4f22816..cbe5674 100644
--- a/tests/test_frontend_setuptools.py
+++ b/tests/test_frontend_setuptools.py
@@ -72,8 +72,7 @@ def test_setuptools_prepare_metadata_for_build_wheel(frontend_setuptools: Subpro
     assert list(dist.entry_points) == [EntryPoint(name="demo_exe", value="demo:a", group="console_scripts")]
     assert dist.version == "1.0"
     assert dist.metadata["Name"] == "demo"
-    values = [v for k, v in dist.metadata.items() if k == "Requires-Dist"]  # type: ignore[attr-defined]
-    # ignore because "PackageMetadata" has no attribute "items"
+    values = dist.metadata.get_all("Requires-Dist") or []
     expected = ["magic>3", "requests>2"] if sys.version_info[0:2] > (3, 8) else ["magic >3", "requests >2"]
     assert sorted(values) == expected
     assert isinstance(result.out, str)