diff --git a/homeassistant/components/config/zwave.py b/homeassistant/components/config/zwave.py
index c01f22f0207..1f52e4f5e9a 100644
--- a/homeassistant/components/config/zwave.py
+++ b/homeassistant/components/config/zwave.py
@@ -74,5 +74,5 @@ def _read(path):
 
 def _write(path, data):
     """Write YAML helper."""
-    with open(path, 'w') as outfile:
-        dump(data, outfile)
+    with open(path, 'w', encoding='utf-8') as outfile:
+        outfile.write(dump(data))
diff --git a/homeassistant/util/yaml.py b/homeassistant/util/yaml.py
index 8100c6e5f68..15366f1b670 100644
--- a/homeassistant/util/yaml.py
+++ b/homeassistant/util/yaml.py
@@ -69,9 +69,9 @@ def load_yaml(fname: str) -> Union[List, Dict]:
         raise HomeAssistantError(exc)
 
 
-def dump(_dict: dict, outfile=None) -> str:
+def dump(_dict: dict) -> str:
     """Dump yaml to a string and remove null."""
-    return yaml.safe_dump(_dict, outfile, default_flow_style=False) \
+    return yaml.safe_dump(_dict, default_flow_style=False) \
         .replace(': null\n', ':\n')