diff --git a/esphome/build_gen/build_tool.py b/esphome/build_gen/build_tool.py
index d20fe78673..608c316e83 100644
--- a/esphome/build_gen/build_tool.py
+++ b/esphome/build_gen/build_tool.py
@@ -85,7 +85,11 @@ def _run_copy(src: str, dst: str) -> int:
 
 
 def _run_touch(path: str) -> int:
-    Path(path).touch()
+    try:
+        Path(path).touch()
+    except OSError as err:
+        print(f"touch: {path} failed: {err}", file=sys.stderr)
+        return 1
     return 0
 
 
diff --git a/tests/unit_tests/build_gen/test_build_tool.py b/tests/unit_tests/build_gen/test_build_tool.py
index 5beef92b10..9bc44bc149 100644
--- a/tests/unit_tests/build_gen/test_build_tool.py
+++ b/tests/unit_tests/build_gen/test_build_tool.py
@@ -254,3 +254,11 @@ def test_touch_creates_and_updates_stamp(tmp_path: Path) -> None:
     os.utime(stamp, (1, 1))
     assert build_tool._run_touch(str(stamp)) == 0
     assert stamp.stat().st_mtime > 1
+
+
+def test_touch_reports_failure(
+    tmp_path: Path, capsys: pytest.CaptureFixture[str]
+) -> None:
+    missing_dir = tmp_path / "gone" / "stamp"
+    assert build_tool._run_touch(str(missing_dir)) == 1
+    assert "touch:" in capsys.readouterr().err
diff --git a/tests/unit_tests/test_platformio_pch_script.py b/tests/unit_tests/test_platformio_pch_script.py
index d2eaf80161..214a4f26af 100644
--- a/tests/unit_tests/test_platformio_pch_script.py
+++ b/tests/unit_tests/test_platformio_pch_script.py
@@ -478,7 +478,10 @@ def test_pch_script_strict_tables_match_helpers(tmp_path: Path) -> None:
 
     proj = tmp_path / "dev"
     (proj / "src").mkdir(parents=True)
-    env = _FakeSConsEnv(proj, proj / "src", "g++", ["-DX=1"])
+    # Hermetic: the constants are module-level, but the exec still runs
+    # _setup_pch, which must not touch the host toolchain
+    cxx = _fake_cxx(tmp_path)
+    env = _FakeSConsEnv(proj, proj / "src", str(cxx), ["-DX=1"])
     namespace = {"Import": lambda *_names: None, "env": env, "projenv": env}
     with patch.dict(os.environ, {}, clear=True):
         exec(compile(_SCRIPT.read_text(), "pch.py", "exec"), namespace)  # noqa: S102