diff --git a/hassio/addons/validate.py b/hassio/addons/validate.py
index 6bdfafc63..0cd1aa4e5 100644
--- a/hassio/addons/validate.py
+++ b/hassio/addons/validate.py
@@ -9,7 +9,7 @@ from ..const import (
     ARCH_AARCH64, ARCH_AMD64, ARCH_I386)
 
 
-MAP_VOLUME = r"^(config|ssl|addons|backup)(:rw|:ro)?$"
+MAP_VOLUME = r"^(config|ssl|addons|backup)(?::(rw|:ro))?$"
 
 V_STR = 'str'
 V_INT = 'int'