diff --git a/homeassistant/components/cec.py b/homeassistant/components/cec.py
index 0034eb131b6..0c7c40c1214 100644
--- a/homeassistant/components/cec.py
+++ b/homeassistant/components/cec.py
@@ -46,7 +46,7 @@ def parse_mapping(mapping, parents=None):
 
 
 def pad_physical_address(addr):
-    """Right-pad a physical address"""
+    """Right-pad a physical address."""
     return addr + ['0'] * (MAX_DEPTH - len(addr))