diff --git a/gapi.xsd b/gapi.xsd
index 7eae62f9a..af09aca5a 100644
--- a/gapi.xsd
+++ b/gapi.xsd
@@ -214,7 +214,7 @@
         <xs:attribute name="cname" type="xs:string"/>
         <xs:attribute name="type" type="xs:string"/>
         <xs:attribute name="array" type="xs:boolean" use="optional"/>
-        <xs:attribute name="array_len" type="xs:string" use="optional"/>
+        <xs:attribute name="array_len" type="xs:positiveInteger" use="optional"/>
         <xs:attribute name="hidden" type="xs:boolean" use="optional"/>
         <xs:attribute name="access" type="xs:string" use="optional"/>
         <xs:attribute name="writeable" type="xs:boolean" use="optional"/>