diff --git a/src/as/com/threerings/util/ArrayUtil.as b/src/as/com/threerings/util/ArrayUtil.as
index e2cf2b9df..c1093b8df 100644
--- a/src/as/com/threerings/util/ArrayUtil.as
+++ b/src/as/com/threerings/util/ArrayUtil.as
@@ -228,6 +228,14 @@ public class ArrayUtil
         return true;
     }
 
+    /**
+     * Copy a segment of one array to another.
+     * @param src the array to copy from
+     * @param srcoffset the position in the source array to begin copying from
+     * @param dst the array to copy into
+     * @param dstoffset the position in the destition array to begin copying into
+     * @param count the number of elements to copy
+     */
     public static function copy (
         src :Array, srcoffset :uint, dst :Array, dstoffset :uint, count :uint) :void
     {
diff --git a/src/as/com/threerings/util/Throttle.as b/src/as/com/threerings/util/Throttle.as
index 48857fbb2..082c4e333 100644
--- a/src/as/com/threerings/util/Throttle.as
+++ b/src/as/com/threerings/util/Throttle.as
@@ -83,6 +83,7 @@ public class Throttle
             // copy to a larger buffer, leaving zeroes at the beginning
             oldestOp = _oldestOp + operations - _ops.length;
             ArrayUtil.copy(_ops, 0, ops, 0, _oldestOp);
+            ArrayUtil.copy(_ops, _oldestOp, ops, oldestOp, _ops.length - _oldestOp);
 
         } else if (operations < _ops.length) {
             // copy to a smaller buffer, truncating older operations