diff --git a/lib/run-task.js b/lib/run-task.js
index 5a12931..7916f61 100644
--- a/lib/run-task.js
+++ b/lib/run-task.js
@@ -10,6 +10,7 @@
 // Requirements
 // ------------------------------------------------------------------------------
 
+const fs = require('fs')
 const path = require('path')
 const parseArgs = require('shell-quote').parse
 const createHeader = require('./create-header')
@@ -128,6 +129,9 @@ function cleanTaskArg (arg) {
  *   An array of options which are inserted before the task name.
  * @param {object} options.labelState - A state object for printing labels.
  * @param {boolean} options.printName - The flag to print task names before running each task.
+ * @param {object} options.packageInfo - A package.json's information.
+ * @param {object} options.packageInfo.body - A package.json's JSON object.
+ * @param {string} options.packageInfo.path - A package.json's file path.
  * @returns {Promise}
  *   A promise object which becomes fullfilled when the npm-script is completed.
  *   This promise object has an extra method: `abort()`.
@@ -156,12 +160,37 @@ module.exports = function runTask (task, options) {
       }
 
       // Execute.
-      const npmPath = options.npmPath || path.basename(process.env.npm_execpath).startsWith('npx') // eslint-disable-line no-process-env
-        ? path.join(path.dirname(process.env.npm_execpath), path.basename(process.env.npm_execpath).replace('npx', 'npm')) // eslint-disable-line no-process-env
-        : process.env.npm_execpath // eslint-disable-line no-process-env
-      const npmPathIsJs = typeof npmPath === 'string' && /\.m?js/.test(path.extname(npmPath))
-      const execPath = (npmPathIsJs ? process.execPath : npmPath || 'npm')
+      let npmPath = options.npmPath
+      if (!npmPath && process.env.npm_execpath) {
+        const basename = path.basename(process.env.npm_execpath)
+        let newBasename = basename
+        if (basename.startsWith('npx')) {
+          newBasename = basename.replace('npx', 'npm') // eslint-disable-line no-process-env
+        } else if (basename.startsWith('pnpx')) {
+          newBasename = basename.replace('pnpx', 'pnpm') // eslint-disable-line no-process-env
+        }
+
+        npmPath = newBasename === basename
+          ? path.join(path.dirname(process.env.npm_execpath), newBasename)
+          : process.env.npm_execpath // eslint-disable-line no-process-env
+      }
+
+      const npmPathIsJs = typeof npmPath === 'string' && /\.(c|m)?js/.test(path.extname(npmPath))
+      let execPath = (npmPathIsJs ? process.execPath : npmPath || 'npm')
+
+      if (!npmPath && !process.env.npm_execpath) {
+        // When a script is being run via pnpm, npmPath and npm_execpath will be null or undefined
+        // Attempt to figure out whether we're running via pnpm
+        const projectRoot = path.dirname(options.packageInfo.path)
+        const hasPnpmLockfile = fs.existsSync(path.join(projectRoot, 'pnpm-lock.yaml'))
+        const { status: pnpmFound, output } = spawn.sync('which', 'pnpm', { silent: true })
+        if (hasPnpmLockfile && __dirname.split(path.delimiter).includes('.pnpm') && pnpmFound) {
+          execPath = output
+        }
+      }
+
       const isYarn = process.env.npm_config_user_agent && process.env.npm_config_user_agent.startsWith('yarn') // eslint-disable-line no-process-env
+
       const spawnArgs = ['run']
 
       if (npmPathIsJs) {
diff --git a/lib/spawn-posix.js b/lib/spawn-posix.js
index 6d63549..ca5a851 100644
--- a/lib/spawn-posix.js
+++ b/lib/spawn-posix.js
@@ -55,9 +55,25 @@ function kill () {
  * @returns {ChildProcess} A ChildProcess instance of new process.
  * @private
  */
-module.exports = function spawn (command, args, options) {
+function spawn (command, args, options) {
   const child = crossSpawn(command, args, options)
   child.kill = kill
 
   return child
 }
+
+/**
+ * Launches a new process synchronously with the given command.
+ * This is almost same as `child_process.spawnSync`.
+ *
+ * This returns a `SpawnSyncReturns` object.
+ *
+ * @param {string} command - The command to run.
+ * @param {string[]} args - List of string arguments.
+ * @param {object} options - Options.
+ * @returns {SpawnSyncReturns} A ChildProcess instance of new process.
+ * @private
+ */
+spawn.sync = crossSpawn.sync
+
+module.exports = spawn
diff --git a/lib/spawn-win32.js b/lib/spawn-win32.js
index 1198d98..4cc26b5 100644
--- a/lib/spawn-win32.js
+++ b/lib/spawn-win32.js
@@ -42,9 +42,25 @@ function kill () {
  * @returns {ChildProcess} A ChildProcess instance of new process.
  * @private
  */
-module.exports = function spawn (command, args, options) {
+function spawn (command, args, options) {
   const child = crossSpawn(command, args, options)
   child.kill = kill
 
   return child
 }
+
+/**
+ * Launches a new process synchronously with the given command.
+ * This is almost same as `child_process.spawnSync`.
+ *
+ * This returns a `SpawnSyncReturns` object.
+ *
+ * @param {string} command - The command to run.
+ * @param {string[]} args - List of string arguments.
+ * @param {object} options - Options.
+ * @returns {SpawnSyncReturns} A ChildProcess instance of new process.
+ * @private
+ */
+spawn.sync = crossSpawn.sync
+
+module.exports = spawn