diff --git a/tests/unit_tests/core/test_config.py b/tests/unit_tests/core/test_config.py
index e520db9e33..4c543bff9c 100644
--- a/tests/unit_tests/core/test_config.py
+++ b/tests/unit_tests/core/test_config.py
@@ -384,6 +384,8 @@ def test_preload_core_config_basic(setup_core: Path) -> None:
     assert platform == "esp32"
     assert KEY_CORE in CORE.data
     assert CONF_BUILD_PATH in config[CONF_ESPHOME]
+    # Verify default build path is "build/<device_name>"
+    assert config[CONF_ESPHOME][CONF_BUILD_PATH].endswith("build/test_device")
 
 
 def test_preload_core_config_with_build_path(setup_core: Path) -> None:
@@ -418,6 +420,8 @@ def test_preload_core_config_env_build_path(setup_core: Path) -> None:
 
     assert CONF_BUILD_PATH in config[CONF_ESPHOME]
     assert "test_device" in config[CONF_ESPHOME][CONF_BUILD_PATH]
+    # Verify it uses the env var path with device name appended
+    assert config[CONF_ESPHOME][CONF_BUILD_PATH].endswith("/env/build/test_device")
     assert platform == "rp2040"