diff --git a/packages/docusaurus/src/client/exports/__tests__/isInternalUrl.ts b/packages/docusaurus/src/client/exports/__tests__/isInternalUrl.ts
index bc0833dd89..1d7bef97da 100644
--- a/packages/docusaurus/src/client/exports/__tests__/isInternalUrl.ts
+++ b/packages/docusaurus/src/client/exports/__tests__/isInternalUrl.ts
@@ -27,4 +27,12 @@ describe('isInternalUrl', () => {
   test('should be false for whatever protocol links', () => {
     expect(isInternalUrl('//foo.com')).toBeFalsy();
   });
+
+  test('should be false for telephone links', () => {
+    expect(isInternalUrl('tel:+1234567890')).toBeFalsy();
+  });
+
+  test('should be false for mailto links', () => {
+    expect(isInternalUrl('mailto:someone@example.com')).toBeFalsy();
+  });
 });
diff --git a/packages/docusaurus/src/client/exports/isInternalUrl.js b/packages/docusaurus/src/client/exports/isInternalUrl.js
index 182de277fe..9e7acfc818 100644
--- a/packages/docusaurus/src/client/exports/isInternalUrl.js
+++ b/packages/docusaurus/src/client/exports/isInternalUrl.js
@@ -6,5 +6,5 @@
  */
 
 export default function isInternalUrl(url) {
-  return /^(https?:|\/\/)/.test(url) === false;
+  return /^(https?:|\/\/|mailto:|tel:)/.test(url) === false;
 }