diff --git a/src/main/org/apache/tools/ant/IntrospectionHelper.java b/src/main/org/apache/tools/ant/IntrospectionHelper.java
index b444edcee..a0792f940 100644
--- a/src/main/org/apache/tools/ant/IntrospectionHelper.java
+++ b/src/main/org/apache/tools/ant/IntrospectionHelper.java
@@ -257,7 +257,7 @@ public class IntrospectionHelper implements BuildListener {
                         particular order.
                     */
                 }
-                AttributeSetter as = createAttributeSetter(m, args[0]);
+                AttributeSetter as = createAttributeSetter(m, args[0], propName);
                 if (as != null) {
                     attributeTypes.put(propName, args[0]);
                     attributeSetters.put(propName, as);
@@ -723,12 +723,15 @@ public class IntrospectionHelper implements BuildListener {
      *          Must not be <code>null</code>.
      * @param arg The type of the single argument of the bean's method.
      *            Must not be <code>null</code>.
+     * @param attrName the name of the attribute for which the setter is being
+     *                 created.
      * 
      * @return an appropriate AttributeSetter instance, or <code>null</code>
      *         if no appropriate conversion is available.
      */
     private AttributeSetter createAttributeSetter(final Method m,
-                                                  Class arg) {
+                                                  Class arg, 
+                                                  final String attrName) {
         // use wrappers for primitive classes, e.g. int and 
         // Integer are treated identically
         final Class reflectedArg = PRIMITIVE_TYPE_MAP.containsKey (arg) 
@@ -748,6 +751,11 @@ public class IntrospectionHelper implements BuildListener {
             return new AttributeSetter() {
                     public void set(Project p, Object parent, String value)
                         throws InvocationTargetException, IllegalAccessException {
+                        if (value.length() == 0) {
+                            throw new BuildException("The value \"\" is not a " 
+                                + "legal value for attribute \"" 
+                                + attrName + "\"");
+                        }
                         m.invoke(parent, new Character[] {new Character(value.charAt(0))});
                     }
 
diff --git a/src/main/org/apache/tools/ant/filters/ReplaceTokens.java b/src/main/org/apache/tools/ant/filters/ReplaceTokens.java
index 671d0da67..92c547e37 100644
--- a/src/main/org/apache/tools/ant/filters/ReplaceTokens.java
+++ b/src/main/org/apache/tools/ant/filters/ReplaceTokens.java
@@ -1,7 +1,7 @@
 /*
  * The Apache Software License, Version 1.1
  *
- * Copyright (c) 2002 The Apache Software Foundation.  All rights
+ * Copyright (c) 2002-2003 The Apache Software Foundation.  All rights
  * reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -57,6 +57,7 @@ import java.io.IOException;
 import java.io.Reader;
 import java.util.Hashtable;
 import org.apache.tools.ant.types.Parameter;
+import org.apache.tools.ant.BuildException;
 
 /**
  * Replaces tokens in the original input with user-supplied values.
@@ -303,9 +304,18 @@ public final class ReplaceTokens
                     final String type = params[i].getType();
                     if ("tokenchar".equals(type)) {
                         final String name = params[i].getName();
+                        String value = params[i].getValue();
                         if ("begintoken".equals(name)) {
+                            if (value.length() == 0) {
+                                throw new BuildException("Begin token cannot " 
+                                    + "be empty");
+                            }
                             beginToken = params[i].getValue().charAt(0);
                         } else if ("endtoken".equals(name)) {
+                            if (value.length() == 0) {
+                                throw new BuildException("End token cannot " 
+                                    + "be empty");
+                            }
                             endToken = params[i].getValue().charAt(0);
                         }
                     } else if ("token".equals(type)) {