diff --git a/build.xml b/build.xml
index e17f4e51f..0c7668930 100644
--- a/build.xml
+++ b/build.xml
@@ -1547,6 +1547,22 @@
 
     <!-- Used by AntlibTest.testAntlibResource: -->
     <jar jarfile="${build.tests}/org/apache/tools/ant/taskdefs/test2-antlib.jar">
+      <manifest>
+        <attribute name="Extension-name"
+          value="org.apache.tools.ant"/>
+        <attribute name="Specification-Title"
+          value="Apache Ant"/>
+        <attribute name="Specification-Version"
+          value="${manifest-version}"/>
+        <attribute name="Specification-Vendor"
+          value="Apache Software Foundation"/>
+        <attribute name="Implementation-Title"
+          value="org.apache.tools.ant"/>
+        <attribute name="Implementation-Version"
+          value="${manifest-version}"/>
+        <attribute name="Implementation-Vendor"
+          value="Apache Software Foundation"/>
+      </manifest>
       <zipfileset dir="${tests.etc.dir}" fullpath="taskdefs/test.antlib.xml">
         <include name="taskdefs/test2.antlib.xml"/>
       </zipfileset>
diff --git a/docs/manual/CoreTasks/jar.html b/docs/manual/CoreTasks/jar.html
index 4c278415b..c4f88c1df 100644
--- a/docs/manual/CoreTasks/jar.html
+++ b/docs/manual/CoreTasks/jar.html
@@ -73,14 +73,17 @@ attribute of a zipfileset in a Zip task. The one difference is that if the
 include an empty one for you.)</p>
 
 <p>Manifests are processed by the Jar task according to the
-<a href="http://java.sun.com/j2se/1.3/docs/guide/jar/jar.html">Jar file specification.</a>
+<a target="_blank" href="http://java.sun.com/j2se/1.3/docs/guide/jar/jar.html">Jar file specification.</a>
 Note in particular that this may result in manifest lines greater than 72 bytes
-being wrapped and continued on the next line.
-</p>
+being wrapped and continued on the next line.</p>
+
+<p>The Jar task checks whether you specified package information according to the
+<a target="_blank" href="http://java.sun.com/j2se/1.3/docs/guide/versioning/spec/VersioningSpecification.html#PackageVersioning">
+versioning specification</a>.</p>
 
 <p><b>Please note that the zip format allows multiple files of the same
-fully-qualified name to exist within a single archive.  This has been
-documented as causing various problems for unsuspecting users.  If you wish
+fully-qualified name to exist within a single archive. This has been
+documented as causing various problems for unsuspecting users. If you wish
 to avoid this behavior you must set the <code>duplicate</code> attribute
 to a value other than its default, <code>"add"</code>.</b></p>
 
diff --git a/src/etc/testcases/taskdefs/jar.xml b/src/etc/testcases/taskdefs/jar.xml
index 5001f29a3..1f12bcc56 100644
--- a/src/etc/testcases/taskdefs/jar.xml
+++ b/src/etc/testcases/taskdefs/jar.xml
@@ -236,5 +236,23 @@
       </indexjars>
     </jar>
   </target>
+    
+  <target name="testNoVersionInfo">
+    <mkdir dir="${tmp.dir}"/>
+    <jar destfile="${tmp.jar}" basedir="${tmp.dir}"/>
+  </target>  
+
+  <!-- see http://java.sun.com/j2se/1.3/docs/guide/versioning/spec/VersioningSpecification.html#PackageVersioning -->  
+  <target name="testHasVersionInfo">
+    <mkdir dir="${tmp.dir}"/>
+    <jar destfile="${tmp.jar}" basedir="${tmp.dir}">
+      <manifest>
+        <attribute name="Implementation-Title"   value="Packaging Version Test"/>
+        <attribute name="Implementation-Version" value="1.0"/>
+        <attribute name="Implementation-Vendor"  value="Apache Software Foundation"/>
+      </manifest>
+    </jar>
+  </target>  
 
+    
 </project>
diff --git a/src/main/org/apache/tools/ant/taskdefs/Jar.java b/src/main/org/apache/tools/ant/taskdefs/Jar.java
index f10098674..e3c6e3d29 100644
--- a/src/main/org/apache/tools/ant/taskdefs/Jar.java
+++ b/src/main/org/apache/tools/ant/taskdefs/Jar.java
@@ -45,6 +45,7 @@ import java.util.zip.ZipFile;
 
 import org.apache.tools.ant.BuildException;
 import org.apache.tools.ant.Project;
+import org.apache.tools.ant.taskdefs.Manifest.Section;
 import org.apache.tools.ant.types.EnumeratedAttribute;
 import org.apache.tools.ant.types.Path;
 import org.apache.tools.ant.types.ResourceCollection;
@@ -76,6 +77,7 @@ public class Jar extends Zip {
 
     /** merged manifests added through addConfiguredManifest */
     private Manifest configuredManifest;
+
     /** shadow of the above if upToDate check alters the value */
     private Manifest savedConfiguredManifest;
 
@@ -158,7 +160,7 @@ public class Jar extends Zip {
         setEncoding("UTF8");
         rootEntries = new Vector();
     }
-
+    
     /**
      * Not used for jar files.
      * @param we not used
@@ -773,6 +775,25 @@ public class Jar extends Zip {
      */
     protected void cleanUp() {
         super.cleanUp();
+        
+        // check against packaging spec
+        // http://java.sun.com/j2se/1.3/docs/guide/versioning/spec/VersioningSpecification.html#PackageVersioning
+        Section mainSection = (configuredManifest==null) ? null : configuredManifest.getMainSection();
+        if (mainSection==null) {
+            log("No Implementation-Title set. (" + getLocation() + ")");
+            log("No Implementation-Version set. (" + getLocation() + ")");
+            log("No Implementation-Vendor set. (" + getLocation() + ")");
+        } else {
+            if (mainSection.getAttribute("Implementation-Title") == null) {
+                log("No Implementation-Title set. (" + getLocation() + ")");
+            }
+            if (mainSection.getAttribute("Implementation-Version") == null) {
+                log("No Implementation-Version set. (" + getLocation() + ")");
+            }
+            if (mainSection.getAttribute("Implementation-Vendor") == null) {
+                log("No Implementation-Vendor set. (" + getLocation() + ")");
+            }
+        }
 
         // we want to save this info if we are going to make another pass
         if (!doubleFilePass || !skipWriting) {
diff --git a/src/tests/junit/org/apache/tools/ant/taskdefs/JarTest.java b/src/tests/junit/org/apache/tools/ant/taskdefs/JarTest.java
index 726956ee8..f5ad7092c 100644
--- a/src/tests/junit/org/apache/tools/ant/taskdefs/JarTest.java
+++ b/src/tests/junit/org/apache/tools/ant/taskdefs/JarTest.java
@@ -267,4 +267,19 @@ public class JarTest extends BuildFileTest {
     public void testIndexJarsPlusJarMarker() {
         executeTarget("testIndexJarsPlusJarMarker");
     }
+    
+    public void testNoVersionInfo() {
+        executeTarget("testNoVersionInfo");
+        assertLogContaining("No Implementation-Title set.");
+        assertLogContaining("No Implementation-Version set.");
+        assertLogContaining("No Implementation-Vendor set.");
+    }
+
+    public void testHasVersionInfo() {
+        executeTarget("testHasVersionInfo");
+        assertFalse( getLog().contains("No Implementation-Title set.") );
+        assertFalse( getLog().contains("No Implementation-Version set.") );
+        assertFalse( getLog().contains("No Implementation-Vendor set.") );
+    }
+    
 }