diff --git a/WHATSNEW b/WHATSNEW
index b68a0359e..ee3c9d955 100644
--- a/WHATSNEW
+++ b/WHATSNEW
@@ -363,6 +363,10 @@ Fixed bugs:
  * The ant shell script should now support MSYS/MinGW as well.
    Bugzilla Report 46936.
 
+ * <signjar> has a new force attribute that allows re-signing of jars
+   that are already signed.
+   Bugzilla Report 46891.
+
 Other changes:
 --------------
  * A HostInfo task was added performing information on hosts, including info on 
diff --git a/contributors.xml b/contributors.xml
index 71228e495..4304d8b8d 100644
--- a/contributors.xml
+++ b/contributors.xml
@@ -927,6 +927,10 @@
     <first>Paulo</first>
     <last>Gaspar</last>
   </name>
+  <name>
+    <first>Pavel</first>
+    <last>Jisl</last>
+  </name>
   <name>
     <first>Paweł</first>
     <last>Zuzelski</last>
diff --git a/docs/manual/CoreTasks/signjar.html b/docs/manual/CoreTasks/signjar.html
index 8bf0147f3..c9aedf748 100644
--- a/docs/manual/CoreTasks/signjar.html
+++ b/docs/manual/CoreTasks/signjar.html
@@ -149,9 +149,15 @@ block</td>
       Must support the same command line options as the Sun JDK
       jarsigner command.
       <em>since Ant 1.8.0</em>.</td>
-    <td align="center" valign="top">all</td>
     <td align="center" valign="top">No</td>
   </tr>  
+  <tr>
+    <td valign="top">force</td>
+    <td valign="top">Whether to force signing of the jar file even if
+      it doesn't seem to be out of date or already signed.
+      <em>since Ant 1.8.0</em>.</td>
+    <td align="center" valign="top">No; default false</td>
+  </tr>  
 </table>
 <h3>Parameters as nested elements</h3>
 <table border="1" cellpadding="2" cellspacing="0">
diff --git a/src/main/org/apache/tools/ant/taskdefs/SignJar.java b/src/main/org/apache/tools/ant/taskdefs/SignJar.java
index 9a6c671fa..40038eb8a 100644
--- a/src/main/org/apache/tools/ant/taskdefs/SignJar.java
+++ b/src/main/org/apache/tools/ant/taskdefs/SignJar.java
@@ -104,6 +104,11 @@ public class SignJar extends AbstractJarSignerTask {
      */
     protected String tsacert;
 
+    /**
+     * force signing even if the jar is already signed.
+     */
+    private boolean force = false;
+
     /**
      * error string for unit test verification: {@value}
      */
@@ -253,6 +258,23 @@ public class SignJar extends AbstractJarSignerTask {
         this.tsacert = tsacert;
     }
 
+    /**
+     * Whether to force signing of a jar even it is already signed.
+     * @since Ant 1.8.0
+     */
+    public void setForce(boolean b) {
+        force = b;
+    }
+
+    /**
+     * Should the task force signing of a jar even it is already
+     * signed?
+     * @since Ant 1.8.0
+     */
+    public boolean isForce() {
+        return force;
+    }
+
     /**
      * sign the jar(s)
      *
@@ -448,7 +470,7 @@ public class SignJar extends AbstractJarSignerTask {
      * @return true if the signedjarFile is considered up to date
      */
     protected boolean isUpToDate(File jarFile, File signedjarFile) {
-        if (null == jarFile || !jarFile.exists()) {
+        if (isForce() || null == jarFile || !jarFile.exists()) {
             //these are pathological cases, but retained in case somebody
             //subclassed us.
             return false;