diff --git a/fetch.xml b/fetch.xml
index 8bf24027d..8bcf5db96 100644
--- a/fetch.xml
+++ b/fetch.xml
@@ -77,6 +77,7 @@
   
   <target name="probe-m2" depends="pick-dest">
     <!-- Look for M2 ant tasks in our classpath-->
+    <property name="m2.artifact" location="${dest.dir}/${m2.jar.name}"/>
     <available property="m2.antlib.found"
       resource="org/apache/maven/artifact/ant/antlib.xml" />
     <condition property="m2.antlib.typefound">
@@ -85,18 +86,48 @@
   </target>
   
 
-  <target name="get-m2" depends="probe-m2,pick-dest" unless="m2.antlib.found">
+  <target name="download-m2" depends="probe-m2,pick-dest" unless="m2.antlib.found">
     <!-- fetch M2 ant tasks into our repository, if it is not there-->
     <get src="${m2.antlib.url}" 
-      dest="${dest.dir}/${m2.jar.name}" 
+      dest="${m2.artifact}" 
       verbose="true"
       usetimestamp="false"/>
+  </target>
+
+  <target name="dont-validate-m2-checksum" depends="probe-m2"
+          if="m2.antlib.found">
+    <property name="checksum.equal" value="true" />
+  </target>
+
+  <target name="validate-m2-checksum" 
+          depends="download-m2,dont-validate-m2-checksum"
+          if="m2.sha1.checksum" unless="m2.antlib.found">
+    <checksum file="${m2.artifact}"
+        algorithm="SHA"
+        property="${m2.sha1.checksum}" 
+        verifyProperty="checksum.equal"/>
+  </target>
+
+  <target name="checksum-mismatch" depends="validate-m2-checksum" 
+          unless="checksum.equal" if="m2.sha1.checksum">
+    <delete file="${m2.artifact}"/>
+    <fail >
+      Failed to verify the downloaded file ${m2.antlib.url}" against the checksum
+      coded into libraries.properties. 
+      The local copy has been deleted, for security reasons
+    </fail>
+  </target>
+
+  <target name="checksum-match" depends="checksum-mismatch"
+          unless="checksum.equal">
     <fail status="0">
-      The Maven2 JAR has been installed; rerun ant to load it. 
+      The Maven2 JAR has been installed; rerun Ant to load it.
     </fail>
-  </target>  
-  
-  
+  </target>
+
+  <target name="get-m2" depends="checksum-match" 
+      description="Download the Maven2 Ant tasks"/> 
+
   <target name="macros" depends="get-m2"
     xmlns:artifact="antlib:org.apache.maven.artifact.ant">
 
diff --git a/lib/libraries.properties b/lib/libraries.properties
index 8802ee686..bc2ac579d 100644
--- a/lib/libraries.properties
+++ b/lib/libraries.properties
@@ -1,13 +1,15 @@
 #this file declares the libraries for use in 
 #a given release of the components
 
-m2.version=2.0
+#if you change this, change the checksum to match
+m2.version=2.0.1
 m2.url=http://ibiblio.org/maven2/
 m2.artifact-name=maven-artifact-ant
 m2.jar.name=${m2.artifact-name}-${m2.version}-dep.jar
 #this is the URL of the antlib library, that is pulled down for everything else.
 m2.antlib.url=${m2.url}/org/apache/maven/${m2.artifact-name}/${m2.version}/${m2.jar.name}
-
+#this is the sha1 checksum of the artifact
+m2.sha1.checksum=7240828f1744c1f9f8b158a026ac368a03f536a3
 
 
 #versions of different libraries. Please keep in alphabetical order, except
@@ -23,7 +25,7 @@ jdepend.version=2.7
 junit.version=3.8.1
 jsch.version=0.1.17
 jython.version=3.8.1
-log4j.version=1.2.12
+log4j.version=1.2.13
 #rhino.version=1.5R5
 oro.version=2.0.8
 regexp.version=1.3