diff --git a/eth_validator_watcher/config.py b/eth_validator_watcher/config.py
index 885331b..08ce95a 100644
--- a/eth_validator_watcher/config.py
+++ b/eth_validator_watcher/config.py
@@ -22,12 +22,24 @@ class Config(BaseSettings):
 
     network: Optional[str] = None
     beacon_url: Optional[str] = None
-    beacon_timeout_sec: Optional[int] = 90
-    metrics_port: Optional[int] = 8000
+    beacon_timeout_sec: Optional[int] = None
+    metrics_port: Optional[int] = None
     start_at: Optional[int] = None
     watched_keys: Optional[List[WatchedKeyConfig]] = None
 
 
+def _default_config() -> Config:
+    """Returns the default configuration.
+    """
+    return Config(
+        network='mainnet',
+        beacon_url='http://localhost:5051/',
+        beacon_timeout_sec=90,
+        metrics_port=8000,
+        watched_keys=[],
+    )
+
+
 def load_config(config_file: str) -> Config:
     """Loads the configuration file from environment and configfile.
 
@@ -51,12 +63,16 @@ def load_config(config_file: str) -> Config:
             config = yaml.load(fh, Loader=yaml.CLoader) or dict()
 
         logging.info(f'validating configuration file')
+        from_default = _default_config().model_dump()
         from_env = Config().model_dump()
         from_file = Config(**config).model_dump()
 
         logging.info(f'merging with environment variables')
-        merged = from_file.copy()
+        merged = from_default.copy()
+
+        merged.update({k: v for k, v in from_file.items() if v})
         merged.update({k: v for k, v in from_env.items() if v})
+
         r = Config(**merged)
 
         logging.info(f'configuration file is ready')
diff --git a/tests/assets/config.null.yaml b/tests/assets/config.null.yaml
index e521bd3..402db79 100644
--- a/tests/assets/config.null.yaml
+++ b/tests/assets/config.null.yaml
@@ -1,4 +1,5 @@
 beacon_url: ~
 beacon_timeout_sec: ~
+metrics_port: ~
 network: ~
 watched_keys: ~
diff --git a/tests/assets/config.yaml b/tests/assets/config.yaml
index d138743..98918c5 100644
--- a/tests/assets/config.yaml
+++ b/tests/assets/config.yaml
@@ -3,6 +3,7 @@
 beacon_url: http://localhost:5051/
 beacon_timeout_sec: 90
 network: holesky
+metrics_port: 4242
 
 watched_keys:
   - public_key: '0x832b8286f5d6535fd941c6c4ed8b9b20d214fc6aa726ce4fba1c9dbb4f278132646304f550e557231b6932aa02cf08d3'
diff --git a/tests/test_config.py b/tests/test_config.py
index 0b98b0b..37aa65b 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -9,20 +9,24 @@ def test_null_config() -> None:
     path = str(Path(assets.__file__).parent / "config.null.yaml")
     config = load_config(path)
 
-    assert config.beacon_url is None
+    assert config.beacon_url == 'http://localhost:5051/'
+    assert config.metrics_port == 8000
     assert config.beacon_timeout_sec == 90
-    assert config.network is None
-    assert config.watched_keys is None
+    assert config.network == 'mainnet'
+
+    assert config.watched_keys == []
 
 
 def test_empty_config() -> None:
     path = str(Path(assets.__file__).parent / "config.empty.yaml")
     config = load_config(path)
 
-    assert config.beacon_url is None
+    assert config.beacon_url == 'http://localhost:5051/'
     assert config.beacon_timeout_sec == 90
-    assert config.network is None
-    assert config.watched_keys is None
+    assert config.metrics_port == 8000
+    assert config.network == 'mainnet'
+
+    assert config.watched_keys == []
 
 
 def test_filled_config() -> None:
@@ -31,6 +35,7 @@ def test_filled_config() -> None:
 
     assert config.beacon_url == 'http://localhost:5051/'
     assert config.beacon_timeout_sec == 90
+    assert config.metrics_port == 4242
     assert config.network == 'holesky'
 
     assert [k.public_key for k in config.watched_keys] == ['0x832b8286f5d6535fd941c6c4ed8b9b20d214fc6aa726ce4fba1c9dbb4f278132646304f550e557231b6932aa02cf08d3']