diff --git a/packages/docusaurus-theme-classic/src/__tests__/utils.test.js b/packages/docusaurus-theme-classic/src/__tests__/utils.test.js
index 3c78736cafd7..bdae0c5259b4 100644
--- a/packages/docusaurus-theme-classic/src/__tests__/utils.test.js
+++ b/packages/docusaurus-theme-classic/src/__tests__/utils.test.js
@@ -19,4 +19,14 @@ describe('isSamePath', () => {
   test('should be false for compared path with double trailing slash', () => {
     expect(isSamePath('/docs', '/docs//')).toBeFalsy();
   });
+
+  test('should be true for twice undefined/null', () => {
+    expect(isSamePath(undefined, undefined)).toBeTruthy();
+    expect(isSamePath(undefined, undefined)).toBeTruthy();
+  });
+
+  test('should be false when one undefined', () => {
+    expect(isSamePath('/docs', undefined)).toBeFalsy();
+    expect(isSamePath(undefined, '/docs')).toBeFalsy();
+  });
 });
diff --git a/packages/docusaurus-theme-classic/src/theme/NavbarItem/DefaultNavbarItem.tsx b/packages/docusaurus-theme-classic/src/theme/NavbarItem/DefaultNavbarItem.tsx
index 738fe0579882..2ba2a7e495bf 100644
--- a/packages/docusaurus-theme-classic/src/theme/NavbarItem/DefaultNavbarItem.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/NavbarItem/DefaultNavbarItem.tsx
@@ -159,7 +159,7 @@ function NavItemMobile({
   const menuListRef = useRef<HTMLUListElement>(null);
   const {pathname} = useLocation();
   const [collapsed, setCollapsed] = useState(
-    () => !items?.filter((item) => item.to).some((item) => isSamePath(item.to, pathname)) ?? true,
+    () => !items?.some((item) => isSamePath(item.to, pathname)) ?? true,
   );
 
   const navLinkClassNames = (extraClassName?: string, isSubList = false) =>
diff --git a/packages/docusaurus-theme-classic/src/utils/index.ts b/packages/docusaurus-theme-classic/src/utils/index.ts
index 54cda35a8d60..d2b769cab124 100644
--- a/packages/docusaurus-theme-classic/src/utils/index.ts
+++ b/packages/docusaurus-theme-classic/src/utils/index.ts
@@ -6,7 +6,12 @@
  */
 
 // Compare the 2 paths, ignoring trailing /
-export const isSamePath = (path1, path2) => {
-  const normalize = (str) => (str?.endsWith('/') ? str : `${str}/`);
-  return  normalize(path1) === normalize(path2);
+export const isSamePath = (
+  path1: string | undefined,
+  path2: string | undefined,
+) => {
+  const normalize = (pathname: string | undefined) => {
+    return !pathname || pathname?.endsWith('/') ? pathname : `${pathname}/`;
+  };
+  return normalize(path1) === normalize(path2);
 };