diff --git a/src/as/com/threerings/presents/dobj/DSet.as b/src/as/com/threerings/presents/dobj/DSet.as
index d871e53cb..7ee6545b9 100644
--- a/src/as/com/threerings/presents/dobj/DSet.as
+++ b/src/as/com/threerings/presents/dobj/DSet.as
@@ -85,7 +85,7 @@ public class DSet
      */
     public function iterator () :Iterator
     {
-        return new ArrayIterator(_entries);
+        return new ArrayIterator(_entries, false);
     }
 
     /**
diff --git a/src/as/com/threerings/util/ArrayIterator.as b/src/as/com/threerings/util/ArrayIterator.as
index daaa8b52c..3029a2195 100644
--- a/src/as/com/threerings/util/ArrayIterator.as
+++ b/src/as/com/threerings/util/ArrayIterator.as
@@ -12,10 +12,11 @@ public class ArrayIterator
     /**
      * Create an ArrayIterator.
      */
-    public function ArrayIterator (arr :Array)
+    public function ArrayIterator (arr :Array, allowRemove :Boolean = true)
     {
         _arr = arr;
         _index = 0;
+        _lastIndex = allowRemove ? -1 : -2;
     }
 
     // documentation inherited from interface Iterator
@@ -27,14 +28,16 @@ public class ArrayIterator
     // documentation inherited from interface Iterator
     public function next () :Object
     {
-        _lastIndex = _index;
+        if (_lastIndex != -2) {
+            _lastIndex = _index;
+        }
         return _arr[_index++];
     }
 
     // documentation inherited from interface Iterator
     public function remove () :void
     {
-        if (_lastIndex == -1) {
+        if (_lastIndex < 0) {
             throw new IllegalOperationError();
 
         } else {
@@ -50,7 +53,8 @@ public class ArrayIterator
     /** The current index. */
     protected var _index :int;
 
-    /** The last-removed index. */
-    protected var _lastIndex :int = -1;
+    /** The last-removed index.
+     * Or -1 for already removed, -2 for no removals allowed. */
+    protected var _lastIndex :int;
 }
 }