diff --git a/src/Resources/schema/schema.xsd b/src/Resources/schema/schema.xsd
index a0d459a..7ae84e4 100644
--- a/src/Resources/schema/schema.xsd
+++ b/src/Resources/schema/schema.xsd
@@ -27,6 +27,7 @@
       </xs:choice>
       <xs:attribute name="id"/>
       <xs:attribute name="key"/>
+      <xs:attribute name="value"/>
       <xs:attribute name="type" use="required" type="xs:NCName"/>
     </xs:complexType>
   </xs:element>