diff --git a/composer.json b/composer.json
index 662f859..acb99ca 100644
--- a/composer.json
+++ b/composer.json
@@ -31,7 +31,7 @@
         "psr-4": {
             "Amp\\Process\\": "lib"
         },
-        "files": ["lib/constants.php"]
+        "files": ["lib/functions.php"]
     },
     "autoload-dev": {
         "psr-4": {
diff --git a/lib/Process.php b/lib/Process.php
index d885f8b..2826b80 100644
--- a/lib/Process.php
+++ b/lib/Process.php
@@ -46,7 +46,7 @@ final class Process
     public function __construct($command, string $cwd = null, array $env = [], array $options = [])
     {
         $command = \is_array($command)
-            ? \implode(" ", \array_map(__NAMESPACE__ . "\\escape_arg", $command))
+            ? \implode(" ", \array_map(__NAMESPACE__ . "\\escapeArguments", $command))
             : (string) $command;
 
         $cwd = $cwd ?? "";
diff --git a/lib/constants.php b/lib/constants.php
deleted file mode 100644
index f8cddcf..0000000
--- a/lib/constants.php
+++ /dev/null
@@ -1,20 +0,0 @@
-<?php
-
-namespace Amp\Process;
-
-const BIN_DIR = __DIR__ . DIRECTORY_SEPARATOR . '..' . DIRECTORY_SEPARATOR . 'bin';
-const IS_WINDOWS = (PHP_OS & "\xDF\xDF\xDF") === 'WIN';
-
-if (IS_WINDOWS) {
-    function escape_arg($arg)
-    {
-        return '"' . \preg_replace_callback('(\\\\*("|$))', function ($m) {
-            return \str_repeat('\\', \strlen($m[0])) . $m[0];
-        }, $arg) . '"';
-    }
-} else {
-    function escape_arg($arg)
-    {
-        return \escapeshellarg($arg);
-    }
-}
diff --git a/lib/functions.php b/lib/functions.php
new file mode 100644
index 0000000..c88fea5
--- /dev/null
+++ b/lib/functions.php
@@ -0,0 +1,34 @@
+<?php
+
+namespace Amp\Process;
+
+const BIN_DIR = __DIR__ . DIRECTORY_SEPARATOR . '..' . DIRECTORY_SEPARATOR . 'bin';
+const IS_WINDOWS = (PHP_OS & "\xDF\xDF\xDF") === 'WIN';
+
+if (IS_WINDOWS) {
+    /**
+     * Escapes the command argument for safe inclusion into a Windows command string.
+     *
+     * @param string $arg
+     *
+     * @return string
+     */
+    function escapeArguments(string $arg): string
+    {
+        return '"' . \preg_replace_callback('(\\\\*("|$))', function (array $m): string {
+            return \str_repeat('\\', \strlen($m[0])) . $m[0];
+        }, $arg) . '"';
+    }
+} else {
+    /**
+     * Escapes the command argument for safe inclusion into a Posix shell command string.
+     *
+     * @param string $arg
+     *
+     * @return string
+     */
+    function escapeArguments(string $arg): string
+    {
+        return \escapeshellarg($arg);
+    }
+}