diff --git a/packages/breadc/src/parser/parser.ts b/packages/breadc/src/parser/parser.ts
index f269f238..901d659e 100644
--- a/packages/breadc/src/parser/parser.ts
+++ b/packages/breadc/src/parser/parser.ts
@@ -36,6 +36,7 @@ export function parseOption(
 ): TreeNode | false {
   const o = token.option();
   const [key, rawV] = o.split('=');
+
   if (context.options.has(key)) {
     const option = context.options.get(key)!;
     const name = camelCase(option.name);
@@ -45,7 +46,17 @@ export function parseOption(
       return option.parse(cursor, token, context);
     } else if (option.type === 'boolean') {
       // Parse boolean option
-      context.result.options[name] = !key.startsWith('no-') ? true : false;
+      const negative = key.startsWith('no-');
+      if (
+        rawV === undefined ||
+        ['true', 'yes', 't', 'y'].includes(rawV.toLowerCase())
+      ) {
+        context.result.options[name] = !negative ? true : false;
+      } else if (['false', 'no', 'f', 'n'].includes(rawV.toLowerCase())) {
+        context.result.options[name] = !negative ? false : true;
+      } else {
+        throw new ParseError(`Unexpected value ${rawV} for ${option.format}`);
+      }
     } else if (option.type === 'string') {
       // Parse string option
       if (rawV !== undefined) {
diff --git a/packages/breadc/test/parse.test.ts b/packages/breadc/test/parse.test.ts
index 481b07cc..682f10b9 100644
--- a/packages/breadc/test/parse.test.ts
+++ b/packages/breadc/test/parse.test.ts
@@ -491,6 +491,82 @@ describe('Option Parser', () => {
     `);
   });
 
+  it('should parse boolean option with value', async () => {
+    const cli = breadc('cli');
+    cli.option('--open');
+    cli.command('').action((o) => o);
+
+    expect(await cli.run(['--open=true'])).toMatchInlineSnapshot(`
+      {
+        "--": [],
+        "open": true,
+      }
+    `);
+
+    expect(await cli.run(['--open=YES'])).toMatchInlineSnapshot(`
+      {
+        "--": [],
+        "open": true,
+      }
+    `);
+
+    expect(await cli.run(['--open=T'])).toMatchInlineSnapshot(`
+    {
+      "--": [],
+      "open": true,
+    }
+  `);
+
+    expect(await cli.run(['--open=y'])).toMatchInlineSnapshot(`
+      {
+        "--": [],
+        "open": true,
+      }
+    `);
+
+    expect(await cli.run(['--open=false'])).toMatchInlineSnapshot(`
+      {
+        "--": [],
+        "open": false,
+      }
+    `);
+
+    expect(await cli.run(['--open=No'])).toMatchInlineSnapshot(`
+      {
+        "--": [],
+        "open": false,
+      }
+    `);
+
+    expect(await cli.run(['--open=f'])).toMatchInlineSnapshot(`
+      {
+        "--": [],
+        "open": false,
+      }
+    `);
+
+    expect(await cli.run(['--open=N'])).toMatchInlineSnapshot(`
+      {
+        "--": [],
+        "open": false,
+      }
+    `);
+
+    expect(await cli.run(['--no-open=true'])).toMatchInlineSnapshot(`
+      {
+        "--": [],
+        "open": false,
+      }
+    `);
+
+    expect(await cli.run(['--no-open=false'])).toMatchInlineSnapshot(`
+      {
+        "--": [],
+        "open": true,
+      }
+    `);
+  });
+
   it('should parse string option', async () => {
     const cli = breadc('cli');
     cli.option('--flag');