diff --git a/build.xml b/build.xml
index f23c8d33a..037fd5310 100644
--- a/build.xml
+++ b/build.xml
@@ -1453,10 +1453,12 @@
                    unless="some.regexp.support"/>
           <exclude name="${ant.package}/types/selectors/ContainsRegexpTest.java"
                    unless="some.regexp.support"/>
-          <exclude name="${optional.package}/RhinoScriptTest.java"
+          <exclude name="${optional.package}/Rhino*.java"
                    unless="bsf.present"/>
-          <exclude name="${optional.package}/RhinoScriptTest.java"
+          <exclude name="${optional.package}/Rhino*.java"
                    unless="rhino.present"/>
+          <exclude name="${optional.package}/script/*.java"
+                   unless="bsf.present"/>
           <exclude name="${optional.package}/script/*.java"
                    unless="rhino.present"/>
           <exclude name="${optional.package}/BeanShellScriptTest.java"
diff --git a/src/etc/testcases/taskdefs/optional/script_reference.xml b/src/etc/testcases/taskdefs/optional/script_reference.xml
new file mode 100644
index 000000000..ad02008b1
--- /dev/null
+++ b/src/etc/testcases/taskdefs/optional/script_reference.xml
@@ -0,0 +1,10 @@
+<project name="test-reference" default="script">
+  <target name="script">
+    <script language="javascript">
+    </script>
+  </target>
+  <target name="def">
+    <taskdef name="my.echo" classname="org.apache.tools.ant.taskdefs.Echo"/>
+    <my.echo id="my.echo.ref" message="hello world"/>
+  </target>
+</project>
diff --git a/src/main/org/apache/tools/ant/util/ScriptRunner.java b/src/main/org/apache/tools/ant/util/ScriptRunner.java
index 4e00064b3..e962bb806 100644
--- a/src/main/org/apache/tools/ant/util/ScriptRunner.java
+++ b/src/main/org/apache/tools/ant/util/ScriptRunner.java
@@ -89,7 +89,15 @@ public class ScriptRunner {
     public void addBeans(Map dictionary) {
         for (Iterator i = dictionary.keySet().iterator(); i.hasNext();) {
             String key = (String) i.next();
-            addBean(key, dictionary.get(key));
+            try {
+                Object val = dictionary.get(key);
+                addBean(key, val);
+            } catch (BuildException ex) {
+                // The key is in the dictionary but cannot be retrieved
+                // This is usually due references that refer to tasks
+                // that have not been taskdefed in the current run.
+                // Ignore
+            }
         }
     }
 
diff --git a/src/testcases/org/apache/tools/ant/taskdefs/optional/RhinoReferenceTest.java b/src/testcases/org/apache/tools/ant/taskdefs/optional/RhinoReferenceTest.java
new file mode 100644
index 000000000..10ae28f92
--- /dev/null
+++ b/src/testcases/org/apache/tools/ant/taskdefs/optional/RhinoReferenceTest.java
@@ -0,0 +1,81 @@
+/*
+ *  The Apache Software License, Version 1.1
+ *
+ *  Copyright (c) 2003 The Apache Software Foundation.  All rights
+ *  reserved.
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions
+ *  are met:
+ *
+ *  1. Redistributions of source code must retain the above copyright
+ *  notice, this list of conditions and the following disclaimer.
+ *
+ *  2. Redistributions in binary form must reproduce the above copyright
+ *  notice, this list of conditions and the following disclaimer in
+ *  the documentation and/or other materials provided with the
+ *  distribution.
+ *
+ *  3. The end-user documentation included with the redistribution, if
+ *  any, must include the following acknowlegement:
+ *  "This product includes software developed by the
+ *  Apache Software Foundation (http://www.apache.org/)."
+ *  Alternately, this acknowlegement may appear in the software itself,
+ *  if and wherever such third-party acknowlegements normally appear.
+ *
+ *  4. The names "Ant" and "Apache Software
+ *  Foundation" must not be used to endorse or promote products derived
+ *  from this software without prior written permission. For written
+ *  permission, please contact apache@apache.org.
+ *
+ *  5. Products derived from this software may not be called "Apache"
+ *  nor may "Apache" appear in their names without prior written
+ *  permission of the Apache Group.
+ *
+ *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
+ *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ *  DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
+ *  ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ *  USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ *  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ *  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ *  OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ *  SUCH DAMAGE.
+ *  ====================================================================
+ *
+ *  This software consists of voluntary contributions made by many
+ *  individuals on behalf of the Apache Software Foundation.  For more
+ *  information on the Apache Software Foundation, please see
+ *  <http://www.apache.org/>.
+ */
+package org.apache.tools.ant.taskdefs.optional;
+
+import org.apache.tools.ant.BuildFileTest;
+
+/**
+ * Tests using an undefined reference.
+ *
+ * @author Peter Reilly
+ * @since Ant 1.6
+ */
+public class RhinoReferenceTest extends BuildFileTest {
+
+    public RhinoReferenceTest(String name) {
+        super(name);
+    }
+
+    /**
+     * The JUnit setup method
+     */
+    public void setUp() {
+        configureProject(
+            "src/etc/testcases/taskdefs/optional/script_reference.xml");
+    }
+
+    public void testScript() {
+        executeTarget("script");
+    }
+}