diff --git a/package-lock.json b/package-lock.json
index e892a8a..f6fe024 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -9,7 +9,7 @@
       "version": "1.0.0",
       "dependencies": {
         "@astrojs/sitemap": "^3.7.3",
-        "@opendocument/odr-core": "^6.12.0",
+        "@opendocument/odr-core": "^6.13.0",
         "@tailwindcss/vite": "^4.3.3",
         "astro": "^7.2.3",
         "tailwindcss": "^4.3.3"
@@ -1686,9 +1686,9 @@
       }
     },
     "node_modules/@opendocument/odr-core": {
-      "version": "6.12.0",
-      "resolved": "https://registry.npmjs.org/@opendocument/odr-core/-/odr-core-6.12.0.tgz",
-      "integrity": "sha512-YVNj0FxDb3skDsxMHHPdqfLDqNKqelB2wHhQDVoc8BOPWzk1vUZ5YKiBf+8ryOFt6TwoX47hthSOe9z/2DzdIg==",
+      "version": "6.13.0",
+      "resolved": "https://registry.npmjs.org/@opendocument/odr-core/-/odr-core-6.13.0.tgz",
+      "integrity": "sha512-YwzUfiINXs8xyYaC4aMw1fSAu3MoryepXXtkPNe60JB43pOdakVLhZDRwonmy3WTwaxYhN2qdXA3NvfDlT0tFQ==",
       "license": "MPL-2.0",
       "engines": {
         "node": ">=18"
diff --git a/package.json b/package.json
index e8ae3c4..a481f56 100644
--- a/package.json
+++ b/package.json
@@ -14,7 +14,7 @@
   },
   "dependencies": {
     "@astrojs/sitemap": "^3.7.3",
-    "@opendocument/odr-core": "^6.12.0",
+    "@opendocument/odr-core": "^6.13.0",
     "@tailwindcss/vite": "^4.3.3",
     "astro": "^7.2.3",
     "tailwindcss": "^4.3.3"
diff --git a/src/scripts/viewer.ts b/src/scripts/viewer.ts
index 2a86b9a..63fbcff 100644
--- a/src/scripts/viewer.ts
+++ b/src/scripts/viewer.ts
@@ -441,6 +441,11 @@ export function mountViewer({
     in as a diff, and the document - not the html it was rendered into - comes
     out as bytes. The edits stay in the frame either way, so a failure costs the
     visitor nothing but the file.
+
+    The diff goes in as a json string, and stays one: 6.13.0's readme says to
+    hand `edit` the object instead, but the binding underneath is a
+    `std::string` and an object throws `BindingError` there - in 6.13.0 exactly
+    as in 6.12.0. The readme is what is wrong, so this call is left alone.
   */
   async function saveDocument() {
     if (!currentDoc) return;