diff --git a/WHATSNEW b/WHATSNEW
index 413f07f7a..b788c825f 100644
--- a/WHATSNEW
+++ b/WHATSNEW
@@ -238,9 +238,12 @@ Fixed bugs:
 * If the class invoked by the <java> task threw a ClassNotFoundException,
   this was misinterpreted as the specified class itself not being found.
 
+* <echoproperties> setPrefix javadoc claimed null or empty prefix would be
+  ignored; instead an error was thrown.  Bugzilla report 39954.
+
 Other changes:
 --------------
-* took in bugzilla report 39320.
+* Took in bugzilla report 39320.
 
 * Improve compatibility with GNU Classpath and java versions prior to 1.5. Bugzilla 39027.
 
diff --git a/src/etc/testcases/taskdefs/optional/echoproperties.xml b/src/etc/testcases/taskdefs/optional/echoproperties.xml
index 3466642cf..9458b5224 100644
--- a/src/etc/testcases/taskdefs/optional/echoproperties.xml
+++ b/src/etc/testcases/taskdefs/optional/echoproperties.xml
@@ -12,6 +12,10 @@
     <echoproperties />
   </target>
 
+  <target name="testEchoWithEmptyPrefixToLog" depends="setup">
+    <echoproperties prefix=""/>
+  </target>
+
   <target name="testEchoToLogXml" depends="setup">
     <echoproperties format="xml" />
   </target>
diff --git a/src/main/org/apache/tools/ant/taskdefs/optional/EchoProperties.java b/src/main/org/apache/tools/ant/taskdefs/optional/EchoProperties.java
index f392cbbd7..2461bfa71 100644
--- a/src/main/org/apache/tools/ant/taskdefs/optional/EchoProperties.java
+++ b/src/main/org/apache/tools/ant/taskdefs/optional/EchoProperties.java
@@ -1,5 +1,5 @@
 /*
- * Copyright  2002-2005 The Apache Software Foundation
+ * Copyright 2002-2006 The Apache Software Foundation
  *
  *  Licensed under the Apache License, Version 2.0 (the "License");
  *  you may not use this file except in compliance with the License.
@@ -174,10 +174,12 @@ public class EchoProperties extends Task {
      *@param  prefix  The new prefix value
      */
     public void setPrefix(String prefix) {
-        PropertySet ps = new PropertySet();
-        ps.setProject(getProject());
-        ps.appendPrefix(prefix);
-        addPropertyset(ps);
+        if (prefix != null && prefix.length() != 0) {
+            PropertySet ps = new PropertySet();
+            ps.setProject(getProject());
+            ps.appendPrefix(prefix);
+            addPropertyset(ps);
+        }
     }
 
     /**
diff --git a/src/testcases/org/apache/tools/ant/taskdefs/optional/EchoPropertiesTest.java b/src/testcases/org/apache/tools/ant/taskdefs/optional/EchoPropertiesTest.java
index 152f2b2ce..0dd06c6e9 100644
--- a/src/testcases/org/apache/tools/ant/taskdefs/optional/EchoPropertiesTest.java
+++ b/src/testcases/org/apache/tools/ant/taskdefs/optional/EchoPropertiesTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright  2000-2005 The Apache Software Foundation
+ * Copyright 2000-2006 The Apache Software Foundation
  *
  *  Licensed under the Apache License, Version 2.0 (the "License");
  *  you may not use this file except in compliance with the License.
@@ -63,6 +63,10 @@ public class EchoPropertiesTest extends BuildFileTest {
         expectLogContaining("testEchoToLog", "test.property="+TEST_VALUE);
     }
 
+    public void testEchoWithEmptyPrefixToLog() {
+        expectLogContaining("testEchoWithEmptyPrefixToLog", "test.property="+TEST_VALUE);
+    }
+
 
     public void testReadBadFile() {
         expectBuildExceptionContaining( "testReadBadFile",