diff --git a/actions/assemble-docs/dist/index.js b/actions/assemble-docs/dist/index.js
index 46ff888..b6f42d3 100644
--- a/actions/assemble-docs/dist/index.js
+++ b/actions/assemble-docs/dist/index.js
@@ -19208,7 +19208,14 @@ async function upsertVersionsJson(params) {
     }
     versions[versionEntryIndex] = versionEntry;
   } else {
-    versions.push({ path: version2, label: versionLabel, versionInTitle });
+    const newVersionEntry = {
+      path: version2,
+      label: versionLabel
+    };
+    if (versionInTitle) {
+      newVersionEntry.versionInTitle = versionInTitle;
+    }
+    versions.push(newVersionEntry);
   }
   versions = versions.sort((a, b) => {
     if (a.path === LATEST_VERSION_NAME && b.path !== LATEST_VERSION_NAME) {
diff --git a/actions/assemble-docs/src/upsert-versions-json.ts b/actions/assemble-docs/src/upsert-versions-json.ts
index cf84f37..cb31dca 100644
--- a/actions/assemble-docs/src/upsert-versions-json.ts
+++ b/actions/assemble-docs/src/upsert-versions-json.ts
@@ -24,7 +24,14 @@ export async function upsertVersionsJson(params: {
     }
     versions[versionEntryIndex] = versionEntry;
   } else {
-    versions.push({ path: version, label: versionLabel, versionInTitle });
+    const newVersionEntry: VersionEntry = {
+      path: version,
+      label: versionLabel,
+    };
+    if (versionInTitle) {
+      newVersionEntry.versionInTitle = versionInTitle;
+    }
+    versions.push(newVersionEntry);
   }
 
   // Sort versions: latest first, then reverse alphabetically by path