diff --git a/WHATSNEW b/WHATSNEW
index c9b0f376e..245bc460f 100644
--- a/WHATSNEW
+++ b/WHATSNEW
@@ -233,6 +233,9 @@ Fixed bugs:
   or in the top package.
   Bugzilla Report 21915.
 
+* Project.toBoolean(String) now handles null as argument and does not throw a
+  NullPointerException any more.
+
 Other changes:
 --------------
 * All tasks can be used outside of <target>s.  Note that some tasks
@@ -586,7 +589,7 @@ Other changes:
   Bugzilla Report 22533.
 
 * additional shortcuts for ant options (-d --> -debug, -e --> -emacs,
-  -h --> -help, -p --> -projecthelp, -s --> -find)
+  -h --> -help, -p --> -projecthelp, -s --> -find).
 
 Changes from Ant 1.5.3 to Ant 1.5.4
 ===================================
diff --git a/src/main/org/apache/tools/ant/Project.java b/src/main/org/apache/tools/ant/Project.java
index d5f130854..e308286a4 100644
--- a/src/main/org/apache/tools/ant/Project.java
+++ b/src/main/org/apache/tools/ant/Project.java
@@ -1569,16 +1569,15 @@ public class Project {
      * or <code>"yes"</code> is found, ignoring case.
      *
      * @param s The string to convert to a boolean value.
-     *          Must not be <code>null</code>.
      *
      * @return <code>true</code> if the given string is <code>"on"</code>,
      *         <code>"true"</code> or <code>"yes"</code>, or
      *         <code>false</code> otherwise.
      */
     public static boolean toBoolean(String s) {
-        return (s.equalsIgnoreCase("on")
-                || s.equalsIgnoreCase("true")
-                || s.equalsIgnoreCase("yes"));
+        return ("on".equalsIgnoreCase(s)
+                || "true".equalsIgnoreCase(s)
+                || "yes".equalsIgnoreCase(s));
     }
 
     /**
@@ -2097,4 +2096,4 @@ public class Project {
             // is private/protected.
         }
     }
-}
+}
\ No newline at end of file