diff --git a/src/main/org/apache/tools/ant/util/ResourceUtils.java b/src/main/org/apache/tools/ant/util/ResourceUtils.java
index d269ad4cb..7413914d0 100644
--- a/src/main/org/apache/tools/ant/util/ResourceUtils.java
+++ b/src/main/org/apache/tools/ant/util/ResourceUtils.java
@@ -466,7 +466,7 @@ public class ResourceUtils {
                 long count = srcChannel.size();
                 while (position < count) {
                     position +=
-                        srcChannel.transferTo(position, FileUtils.BUF_SIZE,
+                        srcChannel.transferTo(position, count - position,
                                               destChannel);
                 }
             } finally {