diff --git a/README.md b/README.md
index 6a7540e..79ac827 100644
--- a/README.md
+++ b/README.md
@@ -52,7 +52,7 @@ If `run_install` is a YAML string representation of either an object or an array
 
 ### `package_json_file`
 
-**Optional** (_type:_ `string`, _default:_ `package.json`) File path to the `package.json`/[`package.yaml`](https://github.com/pnpm/pnpm/pull/1799) to read "packageManager" configuration.
+**Optional** (_type:_ `string`, _default:_ `package.json`) File path to the `package.json`/[`package.yaml`/`package.json5`](https://github.com/pnpm/pnpm/pull/1799) to read "packageManager" configuration.
 
 ### `standalone`
 
diff --git a/dist/index.js b/dist/index.js
index ff2b4d9..51eb030 100644
Binary files a/dist/index.js and b/dist/index.js differ
diff --git a/package.json b/package.json
index 991c379..1d5a7f0 100644
--- a/package.json
+++ b/package.json
@@ -14,6 +14,7 @@
     "@types/expand-tilde": "^2.0.2",
     "@types/node": "^22.0.0",
     "expand-tilde": "^2.0.2",
+    "json5": "^2.2.3",
     "yaml": "^2.3.4",
     "zod": "^3.22.4"
   },
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index c3b580b..704465f 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -29,6 +29,9 @@ importers:
       expand-tilde:
         specifier: ^2.0.2
         version: 2.0.2
+      json5:
+        specifier: ^2.2.3
+        version: 2.2.3
       yaml:
         specifier: ^2.3.4
         version: 2.7.0
@@ -422,6 +425,11 @@ packages:
     resolution: {integrity: sha512-vK9P5/iUfdl95AI+JVyUuIcVtd4ofvtrOr3HNtM2yxC9bnMbEdp3x01OhQNnjb8IJYi38VlTE3mBXwcfvywuSw==}
     engines: {node: '>= 14'}
 
+  json5@2.2.3:
+    resolution: {integrity: sha512-XmOWe7eyHYH14cLdVPoyg+GOH3rYX++KpzrylJwSW98t3Nk+U8XOl8FWKOgwtzdb8lXGf6zYwDUzeHMWfxasyg==}
+    engines: {node: '>=6'}
+    hasBin: true
+
   math-intrinsics@1.1.0:
     resolution: {integrity: sha512-/IXtbwEk5HTPyEwyKX6hGkYXxM9nbj64B+ilVJnC/R6B0pH5G4V3b0pVbL7DBj4tkhBAppbQUlf6F6Xl9LHu1g==}
     engines: {node: '>= 0.4'}
@@ -931,6 +939,8 @@ snapshots:
     transitivePeerDependencies:
       - supports-color
 
+  json5@2.2.3: {}
+
   math-intrinsics@1.1.0: {}
 
   mime-db@1.52.0: {}
diff --git a/src/install-pnpm/run.ts b/src/install-pnpm/run.ts
index 1a847af..0b8dc2b 100644
--- a/src/install-pnpm/run.ts
+++ b/src/install-pnpm/run.ts
@@ -6,6 +6,7 @@ import path from 'path'
 import util from 'util'
 import { Inputs } from '../inputs'
 import { parse as parseYaml } from 'yaml'
+import JSON5 from 'json5'
 import pnpmLock from './bootstrap/pnpm-lock.json'
 import exeLock from './bootstrap/exe-lock.json'
 
@@ -93,6 +94,8 @@ function readTargetVersion(opts: {
       const content = readFileSync(path.join(GITHUB_WORKSPACE, packageJsonFile), 'utf8');
       const manifest = packageJsonFile.endsWith(".yaml")
         ? parseYaml(content, { merge: true })
+        : packageJsonFile.endsWith(".json5")
+        ? JSON5.parse(content)
         : JSON.parse(content)
       packageManager = manifest.packageManager
       devEngines = manifest.devEngines