diff --git a/src/selection/join.js b/src/selection/join.js
index f2c508d..67d3a96 100644
--- a/src/selection/join.js
+++ b/src/selection/join.js
@@ -6,7 +6,10 @@ function(onenter, onupdate, onexit) {
   } else {
     enter = enter.append(onenter + "");
   }
-  if (onupdate != null) update = onupdate(update);
+  if (onupdate != null) {
+    update = onupdate(update);
+    if (update) update = update.selection();
+  }
   if (onexit == null) exit.remove(); else onexit(exit);
   return enter && update ? enter.merge(update).order() : update;
 }