diff --git a/packages/office-addin-dev-certs/src/uninstall.ts b/packages/office-addin-dev-certs/src/uninstall.ts
index 215d32f86..1a709c972 100644
--- a/packages/office-addin-dev-certs/src/uninstall.ts
+++ b/packages/office-addin-dev-certs/src/uninstall.ts
@@ -1,12 +1,12 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license.
-
+ 
 import { execSync } from "child_process";
 import * as fsExtra from "fs-extra";
 import * as path from "path";
 import * as defaults from "./defaults";
 import { isCaCertificateInstalled } from "./verify";
-
+ 
 function getUninstallCommand(machine: boolean = false): string {
    switch (process.platform) {
       case "win32":
@@ -18,34 +18,49 @@ function getUninstallCommand(machine: boolean = false): string {
          throw new Error(`Platform not supported: ${process.platform}`);
    }
 }
-
+ 
 // Deletes the generated certificate files and delete the certificate directory if its empty
 export function deleteCertificateFiles(certificateDirectory: string = defaults.certificateDirectory): void {
    if (fsExtra.existsSync(certificateDirectory)) {
       fsExtra.removeSync(path.join(certificateDirectory, defaults.localhostCertificateFileName));
       fsExtra.removeSync(path.join(certificateDirectory, defaults.localhostKeyFileName));
       fsExtra.removeSync(path.join(certificateDirectory, defaults.caCertificateFileName));
-
+ 
       if (fsExtra.readdirSync(certificateDirectory).length === 0) {
          fsExtra.removeSync(certificateDirectory);
       }
    }
 }
-
+ 
 export async function uninstallCaCertificate(machine: boolean = false, verbose: boolean = true) {
    if (isCaCertificateInstalled()) {
       const command = getUninstallCommand(machine);
-
+ 
       try {
-         console.log(`Uninstalling CA certificate "Developer CA for Microsoft Office Add-ins"...`);
-         execSync(command, {stdio : "pipe" });
+         console.log(`Uninstalling CA certificate "Developer CA for Microsoft Office Add-ins"...`);
+         execSync(command, { stdio: "pipe" });
          console.log(`You no longer have trusted access to https://localhost.`);
       } catch (error) {
          throw new Error(`Unable to uninstall the CA certificate.\n${error.stderr.toString()}`);
       }
    } else {
       if (verbose) {
-         console.log(`The CA certificate is not installed.`);
+         console.log(`The CA certificate is not installed.`);
       }
    }
 }
+ 
+// Currently this method is only intended to be used for Mac due to problems on Mac that occur when CA certificates expire
+export async function uninstallExpiredCaCertificate() {
+   if (process.platform === "darwin") {
+      const command = getUninstallCommand();
+ 
+      try {
+         console.log(`Uninstalling expired CA certificate "Developer CA for Microsoft Office Add-ins".`);
+         execSync(command, { stdio: "pipe" });
+         console.log(`You no longer have trusted access to https://localhost.`);
+      } catch (error) {
+         throw new Error(`Unable to uninstall expired the CA certificate.\n${error.stderr.toString()}`);
+      }
+   }
+}
\ No newline at end of file
diff --git a/packages/office-addin-dev-certs/src/verify.ts b/packages/office-addin-dev-certs/src/verify.ts
index 3471185c2..6f7b83016 100644
--- a/packages/office-addin-dev-certs/src/verify.ts
+++ b/packages/office-addin-dev-certs/src/verify.ts
@@ -1,72 +1,83 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license.
-
+ 
 import { execSync } from "child_process";
 import * as crypto from "crypto";
 import * as fs from "fs";
 import * as path from "path";
 import * as defaults from "./defaults";
-
+import { uninstallExpiredCaCertificate } from './uninstall'
+ 
 function getVerifyCommand(): string {
     switch (process.platform) {
        case "win32":
           const script = path.resolve(__dirname, "..\\scripts\\verify.ps1");
           return `powershell -ExecutionPolicy Bypass -File "${script}" "${defaults.certificateName}"`;
        case "darwin": // macOS
-          return `security find-certificate -c '${defaults.certificateName}' -p | openssl x509 -checkend 86400 -noout`;
+          return `security find-certificate -c '${defaults.certificateName}' -p | openssl x509 -noout`;
        default:
           throw new Error(`Platform not supported: ${process.platform}`);
     }
 }
-
+ 
 export function isCaCertificateInstalled(): boolean {
     const command = getVerifyCommand();
-
+ 
     try {
         const output = execSync(command, {stdio : "pipe" }).toString();
         if (process.platform === "darwin") {
-            return true;
+            // Ceritificate exists. Now check and see if it's expired and remove it if is.
+            try {
+                const command = `security find-certificate -c '${defaults.certificateName}' -p | openssl x509 -checkend 86400 -noout`;
+                execSync(command, {stdio : "pipe" }).toString();
+                return true;
+            }
+            catch {
+                uninstallExpiredCaCertificate()
+                return false;
+            }
+ 
         } else if (output.length !== 0) {
             return true; // powershell command return empty string if the certificate not-found/expired
         }
     } catch (error) {
-        // Mac security command throws error if the certifcate is not-found/expired
+        // Mac security command throws error if the certifcate is not found
     }
-
+ 
     return false;
 }
-
+ 
 function validateCertificateAndKey(certificatePath: string, keyPath: string) {
     let certificate: string = "";
     let key: string = "";
-
+ 
     try {
         certificate = fs.readFileSync(certificatePath).toString();
     } catch (err) {
         throw new Error(`Unable to read the certificate.\n${err}`);
     }
-
+ 
     try {
         key = fs.readFileSync(keyPath).toString();
     } catch (err) {
         throw new Error(`Unable to read the certificate key.\n${err}`);
     }
-
+ 
     let encrypted;
-
+ 
     try {
         encrypted = crypto.publicEncrypt(certificate, Buffer.from("test"));
     } catch (err) {
         throw new Error(`The certificate is not valid.\n${err}`);
     }
-
+ 
     try {
         crypto.privateDecrypt(key, encrypted);
     } catch (err) {
         throw new Error(`The certificate key is not valid.\n${err}`);
     }
 }
-
+ 
 export function verifyCertificates(certificatePath: string = defaults.localhostCertificatePath, keyPath: string = defaults.localhostKeyPath): boolean {
     let isCertificateValid: boolean = true;
     try {
@@ -75,4 +86,4 @@ export function verifyCertificates(certificatePath: string = defaults.localhostC
         isCertificateValid = false;
     }
     return isCertificateValid && isCaCertificateInstalled();
-}
+}
\ No newline at end of file
diff --git a/packages/office-addin-dev-certs/test/test.ts b/packages/office-addin-dev-certs/test/test.ts
index 40a0a39d7..5b8914971 100644
--- a/packages/office-addin-dev-certs/test/test.ts
+++ b/packages/office-addin-dev-certs/test/test.ts
@@ -249,7 +249,7 @@ describe("office-addin-dev-certs", function() {
             sandbox.stub(childProcess, "execSync").callsFake(execSync);
             try {
                 const ret = await verify.isCaCertificateInstalled();
-                assert.strictEqual(execSync.callCount, 1);
+                assert.strictEqual(execSync.callCount, (process.platform === "darwin") ? 2 : 1);
                 assert.strictEqual(ret, true);
             } catch (err) {
                 // not expecting any exception