diff --git a/build.xml b/build.xml
index 669183ab..0f54bdce 100644
--- a/build.xml
+++ b/build.xml
@@ -49,6 +49,12 @@
 	<property name="xalan.dir" value="xalan-j_2_6_0"/>
 	<property name="xml.dir" value="xml"/>
 
+	<taskdef resource="net/sf/antcontrib/antlib.xml">
+		<classpath>
+			<pathelement location="${lib.dir}/ant-contrib-1.0b3.jar"/>
+		</classpath>
+	</taskdef>
+	
 	<!--
 		The entities file contains the individual entity fragment files
 		concatenated together and enclosed in an <Entities> element.
@@ -401,6 +407,25 @@
 			x="extract_member_dates.xsl"/>
 	</target>
 
+	<!--
+		Utility to fold overlong embedded certificates.
+	-->
+	<target name="fold.embedded.certs">
+		<echo>Folding embedded certificates</echo>
+		<for param="file">
+			<path>
+				<fileset dir="${entities.dir}" includes="uk*.xml"/>
+			</path>
+			<sequential>
+				<exec executable="perl" dir="${entities.dir}">
+					<arg value="-i"/>
+					<arg value="${build.dir}/fold_cert.pl"/>
+					<arg value="@{file}"/>
+				</exec>
+			</sequential>
+		</for>
+	</target>
+	
 	<!--
 		Extract embedded certificates
 	-->
diff --git a/build/fold_cert.pl b/build/fold_cert.pl
new file mode 100755
index 00000000..92122cac
--- /dev/null
+++ b/build/fold_cert.pl
@@ -0,0 +1,32 @@
+#!/usr/bin/perl -w
+
+#
+# The input file is a fragment file that may or may not have one
+# or more unfolded X.509 embedded certificates in it.  Fold these
+# to a max of 64 characters per Base64 line, but preserve
+# XML indentation.
+#
+
+$max = 64;	# max chars per line
+
+while (<>) {
+	if (/^(\s*)\<ds:X509Certificate\>(.*)\<\/ds:X509Certificate\>\s*$/) {
+		$sp = $1;
+		$spp = "$1    "; # add four spaces
+		$cert = $2;
+		print "$sp<ds:X509Certificate>\n";
+			while (length($cert) != 0) {
+				$line = $cert;
+				if (length($line) > $max) {
+					$line = substr($line, 0, $max)
+				}
+				print "$spp$line\n";
+				substr($cert, 0, length($line)) = '';
+			}
+		print "$sp</ds:X509Certificate>\n";
+	} else {
+		print $_;
+	}
+}
+
+# end