diff --git a/src/main/org/apache/tools/ant/util/optional/JavaxScriptRunner.java b/src/main/org/apache/tools/ant/util/optional/JavaxScriptRunner.java
index ad5953460..d4171a73f 100644
--- a/src/main/org/apache/tools/ant/util/optional/JavaxScriptRunner.java
+++ b/src/main/org/apache/tools/ant/util/optional/JavaxScriptRunner.java
@@ -105,11 +105,16 @@ public class JavaxScriptRunner extends ScriptRunnerBase {
             return engine.invoke("eval", String.class, getScript());
         } catch (BuildException be) {
             //catch and rethrow build exceptions
-            throw be;
+
+            // this may be a BuildException wrapping a ScriptException
+            // deeply wrapping yet another BuildException - for
+            // example because of self.fail() - see
+            // https://issues.apache.org/bugzilla/show_bug.cgi?id=47509
+            throw unwrap(be);
         } catch (Exception be) {
             //any other exception? Get its cause
             Throwable t = be;
-            Throwable te = (Throwable) ReflectUtil.invoke(be, "getCause");
+            Throwable te = be.getCause();
             if (te != null) {
                 if  (te instanceof BuildException) {
                     throw (BuildException) te;
@@ -140,4 +145,21 @@ public class JavaxScriptRunner extends ScriptRunnerBase {
         }
         return ret;
     }
+
+    /**
+     * Traverse a Throwable's cause(s) and return the BuildException
+     * most deeply nested into it - if any.
+     */
+    private static BuildException unwrap(Throwable t) {
+        BuildException deepest =
+            t instanceof BuildException ? (BuildException) t : null;
+        Throwable current = t;
+        while (current.getCause() != null) {
+            current = current.getCause();
+            if (current instanceof BuildException) {
+                deepest = (BuildException) current;
+            }
+        }
+        return deepest;
+    }
 }
diff --git a/src/tests/antunit/taskdefs/optional/script/scriptdef-test.xml b/src/tests/antunit/taskdefs/optional/script/scriptdef-test.xml
index e8916815e..993b9577d 100644
--- a/src/tests/antunit/taskdefs/optional/script/scriptdef-test.xml
+++ b/src/tests/antunit/taskdefs/optional/script/scriptdef-test.xml
@@ -109,4 +109,17 @@
     <scripttest/>
     <assertPropSet name="property2" />
   </target>
+
+  <target name="testExceptionNesting"
+          description="https://issues.apache.org/bugzilla/show_bug.cgi?id=47509"
+          if="prereqs-ok">
+    <scriptdef name="quickfail" language="javascript">
+      <![CDATA[
+            self.fail("I failed!");
+      ]]>
+    </scriptdef>
+    <au:expectfailure message="I failed!">
+      <quickfail/>
+    </au:expectfailure>
+  </target>
 </project>