diff --git a/WHATSNEW b/WHATSNEW
index 5d9a32755..96b39a9ec 100644
--- a/WHATSNEW
+++ b/WHATSNEW
@@ -28,6 +28,8 @@ Fixed bugs:
 * The "plain" <junit> <formatter> could throw a NullPointerException
   if an error occured in setUp.
 
+* <cab> could hang listcab on large <fileset>s.
+
 Other changes:
 --------------
 
diff --git a/src/main/org/apache/tools/ant/taskdefs/optional/Cab.java b/src/main/org/apache/tools/ant/taskdefs/optional/Cab.java
index 798885d2e..04feb6827 100644
--- a/src/main/org/apache/tools/ant/taskdefs/optional/Cab.java
+++ b/src/main/org/apache/tools/ant/taskdefs/optional/Cab.java
@@ -266,9 +266,6 @@ public class Cab extends MatchingTask {
                                            new String[] {"listcab"}, null,
                                            baseDir, true);
                 OutputStream out = p.getOutputStream();
-                out.write(sb.toString().getBytes());
-                out.flush();
-                out.close();
 
                 // Create the stream pumpers to forward listcab's stdout and stderr to the log
                 // note: listcab is an interactive program, and issues prompts for every new line.
@@ -282,6 +279,10 @@ public class Cab extends MatchingTask {
                 (new Thread(outPump)).start();
                 (new Thread(errPump)).start();
 
+                out.write(sb.toString().getBytes());
+                out.flush();
+                out.close();
+
                 int result = -99; // A wild default for when the thread is interrupted
 
                 try {