diff --git a/build.xml b/build.xml
index 34363abe..5c7a8cb8 100644
--- a/build.xml
+++ b/build.xml
@@ -531,6 +531,8 @@
 					<arg value="${keystore.pass}"/>
 					<arg value="--outFile"/>
 					<arg value="${xml.dir}/@{o}"/>
+					<arg value="--referenceIdAttributeName"/>
+					<arg value="ID"/>
 					<!--
 					<arg value="- -quiet"/>
 					-->
diff --git a/build/uk_master_test.xsl b/build/uk_master_test.xsl
index b230dd45..b179195c 100644
--- a/build/uk_master_test.xsl
+++ b/build/uk_master_test.xsl
@@ -42,7 +42,21 @@
 	
 	<xsl:variable name="now" select="date:date-time()"/>
 	<xsl:variable name="validUntil" select="mdxDates:dateAdd($now, $validityDays)"/>
-	
+	
+	<!--
+		documentID
+		
+		This value is generated from a normalised version of the aggregation instant,
+		transformed so that it can be used as an XML ID value.
+		
+		Strict conformance to the SAML 2.0 metadata specification (section 3.1.2) requires
+		that the signature explicitly references an identifier attribute in the element
+		being signed, in this case the document element.
+	-->
+	<xsl:variable name="normalisedNow" select="mdxDates:dateAdd($now, 0)"/>
+	<xsl:variable name="documentID"
+		select="concat('uk', translate($normalisedNow, ':-', ''))"/>
+
 	<!--
 		Document root.
 	-->
@@ -58,6 +72,9 @@
 		<xsl:copy>
 			<xsl:attribute name="validUntil">
 				<xsl:value-of select="$validUntil"/>
+			</xsl:attribute>
+			<xsl:attribute name="ID">
+				<xsl:value-of select="$documentID"/>
 			</xsl:attribute>
 			<xsl:apply-templates select="@*"/>
 			<xsl:call-template name="document.comment"/>