diff --git a/README.md b/README.md
index b64e1ed..a48c5de 100644
--- a/README.md
+++ b/README.md
@@ -97,6 +97,10 @@ For example `pretty-quick --pattern "**/*.*(js|jsx)"` or `pretty-quick --pattern
 
 Outputs the name of each file right before it is proccessed. This can be useful if Prettier throws an error and you can't identify which file is causing the problem.
 
+## `--bail`
+
+Prevent `git commit` if any files are fixed.
+
 <!-- Undocumented = Unsupported :D
 
 ### `--config`
diff --git a/bin/pretty-quick.js b/bin/pretty-quick.js
index 04d6d5c..780a4d4 100755
--- a/bin/pretty-quick.js
+++ b/bin/pretty-quick.js
@@ -9,8 +9,7 @@ const prettyQuick = require('..').default;
 
 const args = mri(process.argv.slice(2));
 
-let success = true;
-prettyQuick(
+const prettyQuickResult = prettyQuick(
   process.cwd(),
   Object.assign({}, args, {
     onFoundSinceRevision: (scm, revision) => {
@@ -31,7 +30,6 @@ prettyQuick(
 
     onPartiallyStagedFile: file => {
       console.log(`✗ Found ${chalk.bold('partially')} staged file ${file}.`);
-      success = false;
     },
 
     onWriteFile: file => {
@@ -44,12 +42,19 @@ prettyQuick(
   })
 );
 
-if (success) {
+if (prettyQuickResult.success) {
   console.log('✅  Everything is awesome!');
 } else {
-  console.log(
-    '✗ Partially staged files were fixed up.' +
-      ` ${chalk.bold('Please update stage before committing')}.`
-  );
+  if (prettyQuickResult.errors.indexOf('PARTIALLY_STAGED_FILE') !== -1) {
+    console.log(
+      '✗ Partially staged files were fixed up.' +
+        ` ${chalk.bold('Please update stage before committing')}.`
+    );
+  }
+  if (prettyQuickResult.errors.indexOf('BAIL_ON_WRITE') !== -1) {
+    console.log(
+      '✗ File had to be prettified and prettyQuick was set to bail mode.'
+    );
+  }
   process.exit(1); // ensure git hooks abort
 }
diff --git a/src/__tests__/scm-git.test.js b/src/__tests__/scm-git.test.js
index edad1a9..48979ba 100644
--- a/src/__tests__/scm-git.test.js
+++ b/src/__tests__/scm-git.test.js
@@ -212,6 +212,22 @@ describe('with git', () => {
     expect(fs.readFileSync('/bar.md', 'utf8')).toEqual('formatted:# foo');
   });
 
+  test('succeeds if a file was changed and bail is not set', () => {
+    mockGitFs();
+
+    const result = prettyQuick('root', { since: 'banana' });
+
+    expect(result).toEqual({ errors: [], success: true });
+  });
+
+  test('fails if a file was changed and bail is set to true', () => {
+    mockGitFs();
+
+    const result = prettyQuick('root', { since: 'banana', bail: true });
+
+    expect(result).toEqual({ errors: ['BAIL_ON_WRITE'], success: false });
+  });
+
   test('with --staged stages fully-staged files', () => {
     mockGitFs();
 
@@ -255,6 +271,17 @@ describe('with git', () => {
     });
   });
 
+  test('with --staged returns false', () => {
+    const additionalUnstaged = './raz.js\n'; // raz.js is partly staged and partly not staged
+    mockGitFs(additionalUnstaged);
+
+    const result = prettyQuick('root', { since: 'banana', staged: true });
+    expect(result).toEqual({
+      errors: ['PARTIALLY_STAGED_FILE'],
+      success: false,
+    });
+  });
+
   test('without --staged does NOT stage changed files', () => {
     mockGitFs();
 
diff --git a/src/__tests__/scm-hg.test.js b/src/__tests__/scm-hg.test.js
index 1c8eb1f..e87b2e1 100644
--- a/src/__tests__/scm-hg.test.js
+++ b/src/__tests__/scm-hg.test.js
@@ -156,6 +156,22 @@ describe('with hg', () => {
     expect(fs.readFileSync('/bar.md', 'utf8')).toEqual('formatted:# foo');
   });
 
+  test('succeeds if a file was changed and bail is not set', () => {
+    mockHgFs();
+
+    const result = prettyQuick('root', { since: 'banana' });
+
+    expect(result).toEqual({ errors: [], success: true });
+  });
+
+  test('fails if a file was changed and bail is set to true', () => {
+    mockHgFs();
+
+    const result = prettyQuick('root', { since: 'banana', bail: true });
+
+    expect(result).toEqual({ errors: ['BAIL_ON_WRITE'], success: false });
+  });
+
   test('calls onWriteFile with changed files for an array of globstar patterns', () => {
     const onWriteFile = jest.fn();
     mockHgFs();
diff --git a/src/index.js b/src/index.js
index 2ae18d4..c91c507 100644
--- a/src/index.js
+++ b/src/index.js
@@ -13,6 +13,7 @@ export default (
     pattern,
     restage = true,
     branch,
+    bail,
     verbose,
     onFoundSinceRevision,
     onFoundChangedFiles,
@@ -57,18 +58,29 @@ export default (
 
   onFoundChangedFiles && onFoundChangedFiles(changedFiles);
 
+  const failReasons = new Set();
+
   formatFiles(directory, changedFiles, {
     config,
     onWriteFile: file => {
       onWriteFile && onWriteFile(file);
+      if (bail) {
+        failReasons.add('BAIL_ON_WRITE');
+      }
       if (staged && restage) {
         if (wasFullyStaged(file)) {
           scm.stageFile(directory, file);
         } else {
           onPartiallyStagedFile && onPartiallyStagedFile(file);
+          failReasons.add('PARTIALLY_STAGED_FILE');
         }
       }
     },
     onExamineFile: verbose && onExamineFile,
   });
+
+  return {
+    success: failReasons.size === 0,
+    errors: Array.from(failReasons),
+  };
 };