diff --git a/HISTORY.md b/HISTORY.md
index 14780091..81944382 100755
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -13,6 +13,9 @@
 * **Documentation Updates:**
 * **Translation Updates:**
 
+### 2022-03-14
+* gui, byob: refactored library serialization
+
 ### 2022-03-11
 * blocks: fixed an edge case for slot type inferral
 * objects: added "combinations" primitive to the palette
diff --git a/snap.html b/snap.html
index b652db47..ed4a85d9 100755
--- a/snap.html
+++ b/snap.html
@@ -20,10 +20,10 @@
         <script src="src/threads.js?version=2022-03-03"></script>
         <script src="src/objects.js?version=2022-03-11"></script>
         <script src="src/scenes.js?version=2022-03-03"></script>
-        <script src="src/gui.js?version=2022-03-11"></script>
+        <script src="src/gui.js?version=2022-03-14"></script>
         <script src="src/paint.js?version=2021-07-05"></script>
         <script src="src/lists.js?version=2022-02-07"></script>
-        <script src="src/byob.js?version=2022-03-09"></script>
+        <script src="src/byob.js?version=2022-03-14"></script>
         <script src="src/tables.js?version=2022-01-28"></script>
         <script src="src/sketch.js?version=2021-11-03"></script>
         <script src="src/video.js?version=2019-06-27"></script>
diff --git a/src/byob.js b/src/byob.js
index 95b0cccf..c78bb84f 100644
--- a/src/byob.js
+++ b/src/byob.js
@@ -111,7 +111,7 @@ ArgLabelMorph*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.byob = '2022-March-09';
+modules.byob = '2022-March-14';
 
 // Declarations
 
@@ -4311,25 +4311,11 @@ BlockExportDialogMorph.prototype.selectNone = function () {
 // BlockExportDialogMorph ops
 
 BlockExportDialogMorph.prototype.exportBlocks = function () {
-    var globals = this.blocks.filter(def => def.isGlobal),
-        glbStr = globals.length ? this.serializer.serialize(globals, true) : '',
-        locals = this.blocks.filter(def => !def.isGlobal),
-        locStr = locals.length ? this.serializer.serialize(locals, true) : '',
-        ide = this.world().children[0],
-        str;
+    var ide = this.world().children[0];
 
     if (this.blocks.length) {
-        str = '<blocks app="'
-            + this.serializer.app
-            + '" version="'
-            + this.serializer.version
-            + '">'
-            + this.paletteXML()
-            + (globals.length ? glbStr : '')
-            + (locals.length ? ('<local>' + locStr + '</local>') : '')
-            + '</blocks>';
         ide.saveXMLAs(
-            str,
+            ide.blocksLibraryXML(this.blocks),
             (ide.getProjectName() || localize('untitled')) +
                 ' ' +
                 localize('blocks'
@@ -4344,19 +4330,6 @@ BlockExportDialogMorph.prototype.exportBlocks = function () {
     }
 };
 
-BlockExportDialogMorph.prototype.paletteXML = function () {
-    var palette = new Map();
-    this.blocks.forEach(def => {
-        if (SpriteMorph.prototype.customCategories.has(def.category)) {
-            palette.set(
-                def.category,
-                SpriteMorph.prototype.customCategories.get(def.category)
-            );
-        }
-    });
-    return this.serializer.paletteToXML(palette);
-};
-
 // BlockExportDialogMorph layout
 
 BlockExportDialogMorph.prototype.fixLayout
diff --git a/src/gui.js b/src/gui.js
index 07357337..8ba6d0ac 100644
--- a/src/gui.js
+++ b/src/gui.js
@@ -86,7 +86,7 @@ BlockVisibilityDialogMorph, ThreadManager*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.gui = '2022-March-11';
+modules.gui = '2022-March-14';
 
 // Declarations
 
@@ -7389,6 +7389,41 @@ IDE_Morph.prototype.getURL = function (url, callback, responseType) {
     }
 };
 
+// IDE_Morph serialization helper ops
+
+IDE_Morph.prototype.blocksLibraryXML = function (definitions) {
+    // answer an XML string encoding of an array of CustomBlockDefinitions
+    var globals = definitions.filter(def => def.isGlobal),
+        locals = definitions.filter(def => !def.isGlobal),
+        glbStr = globals.length ? this.serializer.serialize(globals, true) : '',
+        locStr = locals.length ? this.serializer.serialize(locals, true) : '';
+
+    return '<blocks app="' +
+        this.serializer.app +
+        '" version="' +
+        this.serializer.version +
+        '">' +
+        this.paletteXML(definitions) +
+        (globals.length ? glbStr : '') +
+        (locals.length ? ('<local>' + locStr + '</local>') : '') +
+        '</blocks>';
+};
+
+IDE_Morph.prototype.paletteXML = function (definitions) {
+    // private - answer an XML string containing the palette information
+    // found in an array of CustomBlockDefinitions
+    var palette = new Map();
+    definitions.forEach(def => {
+        if (SpriteMorph.prototype.customCategories.has(def.category)) {
+            palette.set(
+                def.category,
+                SpriteMorph.prototype.customCategories.get(def.category)
+            );
+        }
+    });
+    return this.serializer.paletteToXML(palette);
+};
+
 // IDE_Morph user dialog shortcuts
 
 IDE_Morph.prototype.showMessage = function (message, secs) {