diff --git a/__tests__/context.test.ts b/__tests__/context.test.ts
index 0f97583..98bfcf6 100644
--- a/__tests__/context.test.ts
+++ b/__tests__/context.test.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import {describe, expect, jest, it, afterEach} from '@jest/globals';
+import {describe, expect, jest, it, afterEach, beforeEach, test} from '@jest/globals';
 import fs from 'fs';
 import os from 'os';
 import path from 'path';
@@ -44,6 +44,34 @@ describe('gitRef', () => {
   });
 });
 
+describe('parseGitRef', () => {
+  const originalEnv = process.env;
+  beforeEach(() => {
+    jest.resetModules();
+    process.env = {
+      ...originalEnv,
+      DOCKER_GIT_CONTEXT_PR_HEAD_REF: ''
+    };
+  });
+  afterEach(() => {
+    process.env = originalEnv;
+  });
+  // prettier-ignore
+  test.each([
+    ['refs/heads/master', '860c1904a1ce19322e91ac35af1ab07466440c37', false, '860c1904a1ce19322e91ac35af1ab07466440c37'],
+    ['master', '860c1904a1ce19322e91ac35af1ab07466440c37', false, '860c1904a1ce19322e91ac35af1ab07466440c37'],
+    ['refs/pull/15/merge', '860c1904a1ce19322e91ac35af1ab07466440c37', false, 'refs/pull/15/merge'],
+    ['refs/heads/master', '', false, 'refs/heads/master'],
+    ['master', '', false, 'master'],
+    ['refs/tags/v1.0.0', '', false, 'refs/tags/v1.0.0'],
+    ['refs/pull/15/merge', '', false, 'refs/pull/15/merge'],
+    ['refs/pull/15/merge', '', true, 'refs/pull/15/head'],
+  ])('given %p and %p, should return %p', async (ref: string, sha: string, prHeadRef: boolean, expected: string) => {
+    process.env.DOCKER_DEFAULT_GIT_CONTEXT_PR_HEAD_REF = prHeadRef ? 'true' : '';
+    expect(Context.parseGitRef(ref, sha)).toEqual(expected);
+  });
+});
+
 describe('gitContext', () => {
   it('returns refs/heads/master', async () => {
     expect(Context.gitContext()).toEqual('https://github.com/docker/actions-toolkit.git#refs/heads/master');
diff --git a/src/context.ts b/src/context.ts
index 5556488..2dc2398 100644
--- a/src/context.ts
+++ b/src/context.ts
@@ -39,16 +39,20 @@ export class Context {
   }
 
   public static gitRef(): string {
-    let gitRef = github.context.ref;
-    if (github.context.sha && gitRef && !gitRef.startsWith('refs/')) {
-      gitRef = `refs/heads/${github.context.ref}`;
+    return Context.parseGitRef(github.context.ref, github.context.sha);
+  }
+
+  public static parseGitRef(ref: string, sha: string): string {
+    const setPullRequestHeadRef: boolean = !!(process.env.DOCKER_DEFAULT_GIT_CONTEXT_PR_HEAD_REF && process.env.DOCKER_DEFAULT_GIT_CONTEXT_PR_HEAD_REF === 'true');
+    if (sha && ref && !ref.startsWith('refs/')) {
+      ref = `refs/heads/${ref}`;
     }
-    if (github.context.sha && !gitRef.startsWith(`refs/pull/`)) {
-      gitRef = github.context.sha;
-    } else if (gitRef.startsWith(`refs/pull/`)) {
-      gitRef = gitRef.replace(/\/merge$/g, '/head');
+    if (sha && !ref.startsWith(`refs/pull/`)) {
+      ref = sha;
+    } else if (ref.startsWith(`refs/pull/`) && setPullRequestHeadRef) {
+      ref = ref.replace(/\/merge$/g, '/head');
     }
-    return gitRef;
+    return ref;
   }
 
   public static gitContext(): string {