diff --git a/source/_docs/configuration/yaml.markdown b/source/_docs/configuration/yaml.markdown
index 4fd7bcf2a70..fa79cd97054 100644
--- a/source/_docs/configuration/yaml.markdown
+++ b/source/_docs/configuration/yaml.markdown
@@ -111,3 +111,13 @@ This means that you've mistakenly entered a tab character, instead of spaces.
 Home Assistant is case sensitive, a state of `'on'` is not the same as `'On'` or `'ON'`. Similarly an entity of `group.Doors` is not the same as `group.doors`.
 
 If you're having trouble, check the case that Home Assistant is reporting in the dev-state menu, under *Developer tools*.
+
+### Booleans 
+
+YAML treats `Y`, `true`, `Yes`, `ON` all as `true` and `n`, `FALSE`, `No`, `off` as `false`. This means that if you want to set the state of an entity to `on` you *must* quote it as `'on'` otherwise it will be translated as setting the state to true. The same applies to `off`.
+
+Not quoting the value may generate an error such as:
+
+```txt
+not a valid value for dictionary value @ data
+```