2 files changed, 4 insertions, 1 deletions
diff --git a/byob.js b/byob.js
index 1a4f1e8..2999dbd 100644
--- a/byob.js
+++ b/byob.js
@@ -105,7 +105,7 @@ CommentMorph, localize, CSlotMorph*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.byob = '2013-April-03';
+modules.byob = '2013-April-04';
 
 // Declarations
 
@@ -1587,6 +1587,8 @@ BlockEditorMorph.prototype.updateDefinition = function () {
         if (head.comment) {
             this.definition.comment = head.comment.fullCopy();
             this.definition.comment.block = true; // serialize in short form
+        } else {
+            this.definition.comment = null;
         }
     }
 
diff --git a/history.txt b/history.txt
index d2dd002..7c3dc95 100755
--- a/history.txt
+++ b/history.txt
@@ -1584,3 +1584,4 @@ ______
 ------
 * loading shared projects in presentation mode, exporting URL for shared projects
 * Selecting "Help" for a custom block now pops up the comment attached to its definition's prototype hat, if any
+* BYOB fix for detaching comments from prototype hat blocks