diff --git a/dist/index.js b/dist/index.js
index cdefa6e..8ea2f0a 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -389,7 +389,8 @@ async function run() {
         const region = core.getInput('aws-region', { required: true });
         const roleToAssume = core.getInput('role-to-assume', { required: false });
         const audience = core.getInput('audience', { required: false });
-        const maskAccountId = core.getBooleanInput('mask-aws-account-id', { required: false });
+        const maskAccountIdInput = core.getInput('mask-aws-account-id', { required: false }) || 'false';
+        const maskAccountId = maskAccountIdInput.toLowerCase() === 'true';
         const roleExternalId = core.getInput('role-external-id', { required: false });
         const webIdentityTokenFile = core.getInput('web-identity-token-file', { required: false });
         const roleDuration = parseInt(core.getInput('role-duration-seconds', { required: false })) || DEFAULT_ROLE_DURATION;
diff --git a/src/index.ts b/src/index.ts
index 63b9aaf..c4dbb5a 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -17,7 +17,8 @@ export async function run() {
     const region = core.getInput('aws-region', { required: true });
     const roleToAssume = core.getInput('role-to-assume', { required: false });
     const audience = core.getInput('audience', { required: false });
-    const maskAccountId = core.getBooleanInput('mask-aws-account-id', { required: false });
+    const maskAccountIdInput = core.getInput('mask-aws-account-id', { required: false }) || 'false';
+    const maskAccountId = maskAccountIdInput.toLowerCase() === 'true';
     const roleExternalId = core.getInput('role-external-id', { required: false });
     const webIdentityTokenFile = core.getInput('web-identity-token-file', { required: false });
     const roleDuration = parseInt(core.getInput('role-duration-seconds', { required: false })) || DEFAULT_ROLE_DURATION;
diff --git a/test/index.test.ts b/test/index.test.ts
index 51415c2..a71c915 100644
--- a/test/index.test.ts
+++ b/test/index.test.ts
@@ -86,7 +86,6 @@ describe('Configure AWS Credentials', () => {
     mockedSTS.reset();
     (fromEnv as jest.Mock).mockReset();
     jest.spyOn(core, 'getMultilineInput').mockImplementation(() => []);
-    jest.spyOn(core, 'getBooleanInput').mockImplementation();
     jest.spyOn(core, 'getIDToken').mockImplementation(async () => Promise.resolve('testtoken'));
     jest.spyOn(core, 'exportVariable').mockImplementation();
     jest.spyOn(core, 'setSecret').mockImplementation();
@@ -139,7 +138,7 @@ describe('Configure AWS Credentials', () => {
 
     expect(mockedSTS.commandCalls(AssumeRoleCommand)).toHaveLength(0);
     expect(core.exportVariable).toHaveBeenCalledTimes(5);
-    expect(core.setSecret).toHaveBeenCalledTimes(3);
+    expect(core.setSecret).toHaveBeenCalledTimes(4);
     expect(core.exportVariable).toHaveBeenCalledWith('AWS_ACCESS_KEY_ID', FAKE_ACCESS_KEY_ID);
     expect(core.setSecret).toHaveBeenCalledWith(FAKE_ACCESS_KEY_ID);
     expect(core.exportVariable).toHaveBeenCalledWith('AWS_SECRET_ACCESS_KEY', FAKE_SECRET_ACCESS_KEY);
@@ -278,7 +277,6 @@ describe('Configure AWS Credentials', () => {
   test('can opt into masking account ID', async () => {
     const mockInputs = { ...CREDS_INPUTS, 'aws-region': 'us-east-1', 'mask-aws-account-id': 'true' };
     jest.spyOn(core, 'getInput').mockImplementation(mockGetInput(mockInputs));
-    jest.spyOn(core, 'getBooleanInput').mockImplementation(() => true);
 
     await run();