diff --git a/WHATSNEW b/WHATSNEW
index 9d9f277f4..5b67ef947 100644
--- a/WHATSNEW
+++ b/WHATSNEW
@@ -75,6 +75,9 @@ Fixed bugs:
 
 Other changes:
 --------------
+* gzip now checks that the zipfile is older than the source file
+  before rebuilding the zipfile. 
+
 * New task <loadfile> to load a whole file into a property
 
 * New task <echoproperties> to list your current properties to the screen
diff --git a/src/etc/testcases/taskdefs/gzip.xml b/src/etc/testcases/taskdefs/gzip.xml
index c62e0577c..a59973505 100644
--- a/src/etc/testcases/taskdefs/gzip.xml
+++ b/src/etc/testcases/taskdefs/gzip.xml
@@ -22,6 +22,11 @@
     <gzip src="../asf-logo.gif" zipfile="asf-logo.gif.gz" />
   </target>
 
+  <target name="testDateCheck">
+    <touch file="asf-logo.gif.gz"/>
+    <gzip src="../asf-logo.gif" zipfile="asf-logo.gif.gz" />
+  </target>
+
   <target name="cleanup">
     <delete file="asf-logo.gif.gz" />
   </target>
diff --git a/src/main/org/apache/tools/ant/taskdefs/Pack.java b/src/main/org/apache/tools/ant/taskdefs/Pack.java
index 09ad4d8f4..5fb9972bc 100644
--- a/src/main/org/apache/tools/ant/taskdefs/Pack.java
+++ b/src/main/org/apache/tools/ant/taskdefs/Pack.java
@@ -83,11 +83,11 @@ public abstract class Pack extends Task {
     }
 
     private void validate() {
-        if (zipFile == null) {
+        if (zipFile == null || zipFile.getName().equals("")) {
             throw new BuildException("zipfile attribute is required", location);
         }
 
-        if (source == null) {
+        if (source == null || source.getName().equals("")) {
             throw new BuildException("src attribute is required", location);
         }
 
@@ -99,8 +99,14 @@ public abstract class Pack extends Task {
 
     public void execute() throws BuildException {
         validate();
-        log("Building: " + zipFile.getAbsolutePath());
-        pack();
+
+        if(zipFile.lastModified() < source.lastModified()){
+            log("Building: " + zipFile.getAbsolutePath());
+            pack();
+        }else{
+            log("Nothing to do: " + zipFile.getAbsolutePath() +
+                " is up to date.");
+        }
     }
 
     private void zipFile(InputStream in, OutputStream zOut)
diff --git a/src/testcases/org/apache/tools/ant/taskdefs/GzipTest.java b/src/testcases/org/apache/tools/ant/taskdefs/GzipTest.java
index b871d68e7..58fa948b8 100644
--- a/src/testcases/org/apache/tools/ant/taskdefs/GzipTest.java
+++ b/src/testcases/org/apache/tools/ant/taskdefs/GzipTest.java
@@ -86,4 +86,25 @@ public class GzipTest extends BuildFileTest {
         expectBuildException("test4", "attribute zipfile invalid");
     }
 
+    public void testGZip(){
+        executeTarget("realTest");
+        String log = getLog();
+        assertTrue("Expecting message starting with 'Building:' but got '"
+            + log + "'", log.startsWith("Building:"));
+        assertTrue("Expecting message ending with 'asf-logo.gif.gz' but got '"
+            + log + "'", log.endsWith("asf-logo.gif.gz"));
+    }
+
+    public void testDateCheck(){
+        executeTarget("testDateCheck");
+        String log = getLog();
+        assertTrue(
+            "Expecting message ending with 'asf-logo.gif.gz is up to date.' but got '" + log + "'",
+            log.endsWith("asf-logo.gif.gz is up to date."));
+    }
+
+    public void tearDown(){
+        executeTarget("cleanup");
+    }
+
 }