diff --git a/package.json b/package.json
index 35649ea67..df09b50bb 100644
--- a/package.json
+++ b/package.json
@@ -131,7 +131,7 @@
     "wcwidth.js": "2.0.0",
     "yaml": "2.9.0",
     "yaml-unist-parser": "3.2.0",
-    "yuku-parser": "0.8.4"
+    "yuku-parser": "0.8.7"
   },
   "devDependencies": {
     "@babel/generator": "8.0.0",
@@ -140,7 +140,7 @@
     "@types/jsesc": "3.0.3",
     "@typescript-eslint/eslint-plugin": "8.67.0",
     "@typescript-eslint/parser": "8.67.0",
-    "@yuku-parser/wasm": "0.8.4",
+    "@yuku-parser/wasm": "0.8.7",
     "base64-arraybuffer-es6": "3.1.0",
     "browserslist": "4.28.8",
     "browserslist-to-esbuild": "2.1.1",
diff --git a/tests/format/typescript/_errors_/function-type/__snapshots__/format.test.js.snap b/tests/format/typescript/_errors_/function-type/__snapshots__/format.test.js.snap
new file mode 100644
index 000000000..372eee9e0
--- /dev/null
+++ b/tests/format/typescript/_errors_/function-type/__snapshots__/format.test.js.snap
@@ -0,0 +1,31 @@
+// Jest Snapshot v1, https://jestjs.io/docs/snapshot-testing
+
+exports[`unparenthesized-in-union-type.ts format[babel-ts] 1`] = `
+"Unexpected token (1:15)
+> 1 | type A = B | () => void;
+    |               ^
+  2 |
+Cause: Unexpected token (1:14)"
+`;
+
+exports[`unparenthesized-in-union-type.ts format[oxc-ts] 1`] = `
+"Unexpected token (1:15)
+> 1 | type A = B | () => void;
+    |               ^
+  2 |"
+`;
+
+exports[`unparenthesized-in-union-type.ts format[typescript] 1`] = `
+"Function type notation must be parenthesized when used in a union type. (1:13)
+> 1 | type A = B | () => void;
+    |             ^
+  2 |
+Cause: Function type notation must be parenthesized when used in a union type."
+`;
+
+exports[`unparenthesized-in-union-type.ts format[yuku-ts] 1`] = `
+"Expected a type, but found ')' (1:15)
+> 1 | type A = B | () => void;
+    |               ^
+  2 |"
+`;
diff --git a/tests/format/typescript/_errors_/function-type/format.test.js b/tests/format/typescript/_errors_/function-type/format.test.js
new file mode 100644
index 000000000..f78aea343
--- /dev/null
+++ b/tests/format/typescript/_errors_/function-type/format.test.js
@@ -0,0 +1 @@
+runFormatTest(import.meta, ["typescript", "babel-ts", "oxc-ts", "yuku-ts"]);
diff --git a/tests/format/typescript/_errors_/function-type/unparenthesized-in-union-type.ts b/tests/format/typescript/_errors_/function-type/unparenthesized-in-union-type.ts
new file mode 100644
index 000000000..e70ae0df4
--- /dev/null
+++ b/tests/format/typescript/_errors_/function-type/unparenthesized-in-union-type.ts
@@ -0,0 +1 @@
+type A = B | () => void;
diff --git a/yarn.lock b/yarn.lock
index 1d3072b76..736ab21ff 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -3017,104 +3017,104 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@yuku-parser/binding-android-arm64@npm:0.8.4":
-  version: 0.8.4
-  resolution: "@yuku-parser/binding-android-arm64@npm:0.8.4"
+"@yuku-parser/binding-android-arm64@npm:0.8.7":
+  version: 0.8.7
+  resolution: "@yuku-parser/binding-android-arm64@npm:0.8.7"
   conditions: os=android & cpu=arm64
   languageName: node
   linkType: hard
 
-"@yuku-parser/binding-darwin-arm64@npm:0.8.4":
-  version: 0.8.4
-  resolution: "@yuku-parser/binding-darwin-arm64@npm:0.8.4"
+"@yuku-parser/binding-darwin-arm64@npm:0.8.7":
+  version: 0.8.7
+  resolution: "@yuku-parser/binding-darwin-arm64@npm:0.8.7"
   conditions: os=darwin & cpu=arm64
   languageName: node
   linkType: hard
 
-"@yuku-parser/binding-darwin-x64@npm:0.8.4":
-  version: 0.8.4
-  resolution: "@yuku-parser/binding-darwin-x64@npm:0.8.4"
+"@yuku-parser/binding-darwin-x64@npm:0.8.7":
+  version: 0.8.7
+  resolution: "@yuku-parser/binding-darwin-x64@npm:0.8.7"
   conditions: os=darwin & cpu=x64
   languageName: node
   linkType: hard
 
-"@yuku-parser/binding-freebsd-x64@npm:0.8.4":
-  version: 0.8.4
-  resolution: "@yuku-parser/binding-freebsd-x64@npm:0.8.4"
+"@yuku-parser/binding-freebsd-x64@npm:0.8.7":
+  version: 0.8.7
+  resolution: "@yuku-parser/binding-freebsd-x64@npm:0.8.7"
   conditions: os=freebsd & cpu=x64
   languageName: node
   linkType: hard
 
-"@yuku-parser/binding-linux-arm-gnu@npm:0.8.4":
-  version: 0.8.4
-  resolution: "@yuku-parser/binding-linux-arm-gnu@npm:0.8.4"
+"@yuku-parser/binding-linux-arm-gnu@npm:0.8.7":
+  version: 0.8.7
+  resolution: "@yuku-parser/binding-linux-arm-gnu@npm:0.8.7"
   conditions: os=linux & cpu=arm & libc=glibc
   languageName: node
   linkType: hard
 
-"@yuku-parser/binding-linux-arm-musl@npm:0.8.4":
-  version: 0.8.4
-  resolution: "@yuku-parser/binding-linux-arm-musl@npm:0.8.4"
+"@yuku-parser/binding-linux-arm-musl@npm:0.8.7":
+  version: 0.8.7
+  resolution: "@yuku-parser/binding-linux-arm-musl@npm:0.8.7"
   conditions: os=linux & cpu=arm & libc=musl
   languageName: node
   linkType: hard
 
-"@yuku-parser/binding-linux-arm64-gnu@npm:0.8.4":
-  version: 0.8.4
-  resolution: "@yuku-parser/binding-linux-arm64-gnu@npm:0.8.4"
+"@yuku-parser/binding-linux-arm64-gnu@npm:0.8.7":
+  version: 0.8.7
+  resolution: "@yuku-parser/binding-linux-arm64-gnu@npm:0.8.7"
   conditions: os=linux & cpu=arm64 & libc=glibc
   languageName: node
   linkType: hard
 
-"@yuku-parser/binding-linux-arm64-musl@npm:0.8.4":
-  version: 0.8.4
-  resolution: "@yuku-parser/binding-linux-arm64-musl@npm:0.8.4"
+"@yuku-parser/binding-linux-arm64-musl@npm:0.8.7":
+  version: 0.8.7
+  resolution: "@yuku-parser/binding-linux-arm64-musl@npm:0.8.7"
   conditions: os=linux & cpu=arm64 & libc=musl
   languageName: node
   linkType: hard
 
-"@yuku-parser/binding-linux-x64-gnu@npm:0.8.4":
-  version: 0.8.4
-  resolution: "@yuku-parser/binding-linux-x64-gnu@npm:0.8.4"
+"@yuku-parser/binding-linux-x64-gnu@npm:0.8.7":
+  version: 0.8.7
+  resolution: "@yuku-parser/binding-linux-x64-gnu@npm:0.8.7"
   conditions: os=linux & cpu=x64 & libc=glibc
   languageName: node
   linkType: hard
 
-"@yuku-parser/binding-linux-x64-musl@npm:0.8.4":
-  version: 0.8.4
-  resolution: "@yuku-parser/binding-linux-x64-musl@npm:0.8.4"
+"@yuku-parser/binding-linux-x64-musl@npm:0.8.7":
+  version: 0.8.7
+  resolution: "@yuku-parser/binding-linux-x64-musl@npm:0.8.7"
   conditions: os=linux & cpu=x64 & libc=musl
   languageName: node
   linkType: hard
 
-"@yuku-parser/binding-win32-arm64@npm:0.8.4":
-  version: 0.8.4
-  resolution: "@yuku-parser/binding-win32-arm64@npm:0.8.4"
+"@yuku-parser/binding-win32-arm64@npm:0.8.7":
+  version: 0.8.7
+  resolution: "@yuku-parser/binding-win32-arm64@npm:0.8.7"
   conditions: os=win32 & cpu=arm64
   languageName: node
   linkType: hard
 
-"@yuku-parser/binding-win32-x64@npm:0.8.4":
-  version: 0.8.4
-  resolution: "@yuku-parser/binding-win32-x64@npm:0.8.4"
+"@yuku-parser/binding-win32-x64@npm:0.8.7":
+  version: 0.8.7
+  resolution: "@yuku-parser/binding-win32-x64@npm:0.8.7"
   conditions: os=win32 & cpu=x64
   languageName: node
   linkType: hard
 
-"@yuku-parser/wasm@npm:0.8.4":
-  version: 0.8.4
-  resolution: "@yuku-parser/wasm@npm:0.8.4"
+"@yuku-parser/wasm@npm:0.8.7":
+  version: 0.8.7
+  resolution: "@yuku-parser/wasm@npm:0.8.7"
   dependencies:
-    "@yuku-toolchain/types": "npm:^0.8.4"
-    yuku-ast: "npm:^0.8.4"
-  checksum: 10/98fb06b3a0e556fdb33af6cde5b5f941eb9f539ae3c4c4c611bd096dced16c8fe7f50e73f936758d4c862957dc845d52f1e16ac3286c78d92a0e9a2e693dfc60
+    "@yuku-toolchain/types": "npm:^0.8.7"
+    yuku-ast: "npm:^0.8.7"
+  checksum: 10/5ded5a2aa273e58de363bb70b3dae51c1e18a05980c64ddda0c65b9b22e6eabcdbf013ab2f28777d20bb09cee604316d00a3cb9085905a3cb8d3445516cc3afd
   languageName: node
   linkType: hard
 
-"@yuku-toolchain/types@npm:^0.8.4":
-  version: 0.8.4
-  resolution: "@yuku-toolchain/types@npm:0.8.4"
-  checksum: 10/4d4d5afcaed2e7d6acfd3c7f36be3911090ed31dd2838147b9aca1065a722a2e9b3de981f179e4031eaa27131148e894ed846dad53b67740f9382fbe363c8677
+"@yuku-toolchain/types@npm:^0.8.7":
+  version: 0.8.7
+  resolution: "@yuku-toolchain/types@npm:0.8.7"
+  checksum: 10/04b1701bb1f60d30b113be7b2553dc2cde498e175c7eaf4dc44f88c659328d47da4a2841761076c6ef22c40e2ca8c8600c8f97fe6c6d11bfe369a0b2bf4fb2be
   languageName: node
   linkType: hard
 
@@ -8231,7 +8231,7 @@ __metadata:
     "@typescript-eslint/parser": "npm:8.67.0"
     "@typescript-eslint/typescript-estree": "npm:8.67.0"
     "@typescript-eslint/visitor-keys": "npm:8.67.0"
-    "@yuku-parser/wasm": "npm:0.8.4"
+    "@yuku-parser/wasm": "npm:0.8.7"
     acorn: "npm:8.18.0"
     acorn-jsx: "npm:5.3.2"
     angular-estree-parser: "npm:15.5.0"
@@ -8358,7 +8358,7 @@ __metadata:
     yaml: "npm:2.9.0"
     yaml-test-suite: "npm:0.1.0"
     yaml-unist-parser: "npm:3.2.0"
-    yuku-parser: "npm:0.8.4"
+    yuku-parser: "npm:0.8.7"
   bin:
     prettier: ./bin/prettier.cjs
   languageName: unknown
@@ -10091,33 +10091,33 @@ __metadata:
   languageName: node
   linkType: hard
 
-"yuku-ast@npm:^0.8.4":
-  version: 0.8.4
-  resolution: "yuku-ast@npm:0.8.4"
+"yuku-ast@npm:^0.8.7":
+  version: 0.8.7
+  resolution: "yuku-ast@npm:0.8.7"
   dependencies:
-    "@yuku-toolchain/types": "npm:^0.8.4"
-  checksum: 10/41447fbe9e0612d97a45f7938a2ca76c7f4918ce5eae6b60081243260147be79b6dd7233aa07b0960eee203ebd2af81b988b26d179dc8172b8848b095442e642
+    "@yuku-toolchain/types": "npm:^0.8.7"
+  checksum: 10/93303e4851eadd4e02a9b09497758fab7f2e131445fa18447096c20fb715a7346cf247f0d7d8c0f34595d8214b14bcad8c83248d5a91994a4825da761f3bb4d2
   languageName: node
   linkType: hard
 
-"yuku-parser@npm:0.8.4":
-  version: 0.8.4
-  resolution: "yuku-parser@npm:0.8.4"
+"yuku-parser@npm:0.8.7":
+  version: 0.8.7
+  resolution: "yuku-parser@npm:0.8.7"
   dependencies:
-    "@yuku-parser/binding-android-arm64": "npm:0.8.4"
-    "@yuku-parser/binding-darwin-arm64": "npm:0.8.4"
-    "@yuku-parser/binding-darwin-x64": "npm:0.8.4"
-    "@yuku-parser/binding-freebsd-x64": "npm:0.8.4"
-    "@yuku-parser/binding-linux-arm-gnu": "npm:0.8.4"
-    "@yuku-parser/binding-linux-arm-musl": "npm:0.8.4"
-    "@yuku-parser/binding-linux-arm64-gnu": "npm:0.8.4"
-    "@yuku-parser/binding-linux-arm64-musl": "npm:0.8.4"
-    "@yuku-parser/binding-linux-x64-gnu": "npm:0.8.4"
-    "@yuku-parser/binding-linux-x64-musl": "npm:0.8.4"
-    "@yuku-parser/binding-win32-arm64": "npm:0.8.4"
-    "@yuku-parser/binding-win32-x64": "npm:0.8.4"
-    "@yuku-toolchain/types": "npm:^0.8.4"
-    yuku-ast: "npm:^0.8.4"
+    "@yuku-parser/binding-android-arm64": "npm:0.8.7"
+    "@yuku-parser/binding-darwin-arm64": "npm:0.8.7"
+    "@yuku-parser/binding-darwin-x64": "npm:0.8.7"
+    "@yuku-parser/binding-freebsd-x64": "npm:0.8.7"
+    "@yuku-parser/binding-linux-arm-gnu": "npm:0.8.7"
+    "@yuku-parser/binding-linux-arm-musl": "npm:0.8.7"
+    "@yuku-parser/binding-linux-arm64-gnu": "npm:0.8.7"
+    "@yuku-parser/binding-linux-arm64-musl": "npm:0.8.7"
+    "@yuku-parser/binding-linux-x64-gnu": "npm:0.8.7"
+    "@yuku-parser/binding-linux-x64-musl": "npm:0.8.7"
+    "@yuku-parser/binding-win32-arm64": "npm:0.8.7"
+    "@yuku-parser/binding-win32-x64": "npm:0.8.7"
+    "@yuku-toolchain/types": "npm:^0.8.7"
+    yuku-ast: "npm:^0.8.7"
   dependenciesMeta:
     "@yuku-parser/binding-android-arm64":
       optional: true
@@ -10143,7 +10143,7 @@ __metadata:
       optional: true
     "@yuku-parser/binding-win32-x64":
       optional: true
-  checksum: 10/bc8d6b687a93561347c3644e29ec3040836791591395217e351b3f2a1db5ec7b23bc3f1d70549ccc9b977f2e65ed07a12b38e7ee22b21cf7dfd559f5a27fa888
+  checksum: 10/875ac80f0a297712a23984648a36c729c16242356d805dab5addee82986a0a5008a10bc966cddb257842c06ff98bcb3a9366a7f8d1654287042b29cdac8ddba2
   languageName: node
   linkType: hard