diff --git a/xml/dtd/pentestreport.xsd b/xml/dtd/pentestreport.xsd
index 37b247a..ac0c519 100644
--- a/xml/dtd/pentestreport.xsd
+++ b/xml/dtd/pentestreport.xsd
@@ -300,7 +300,19 @@
       <xs:attribute name="id" use="required" type="xs:ID"/>
       <xs:attribute ref="xml:base"/>
       <xs:attribute ref="xml:lang"/>
-      <xs:attribute ref="threatLevel" use="optional" default="N/A"/>
+      <xs:attribute name="threatLevel">
+        <xs:simpleType>
+          <xs:restriction base="xs:string">
+            <xs:enumeration value="Extreme"/>
+            <xs:enumeration value="High"/>
+            <xs:enumeration value="Elevated"/>
+            <xs:enumeration value="Moderate"/>
+            <xs:enumeration value="Low"/>
+            <xs:enumeration value="Unknown"/>
+            <xs:enumeration value="NA"/>
+          </xs:restriction>
+        </xs:simpleType>
+      </xs:attribute>
       <xs:attribute name="status" use="optional">
         <xs:simpleType>
           <xs:restriction base="xs:string">