diff --git a/box.json b/box.json
index b4554d6..6887b03 100644
--- a/box.json
+++ b/box.json
@@ -1,5 +1,5 @@
 {
-    "main": "vendor/autoload.php",
+    "main": "phar-stub.php",
     "output": "geoip2.phar",
     "compactors": [
         "Herrera\\Box\\Compactor\\Composer",
diff --git a/phar-stub.php b/phar-stub.php
new file mode 100644
index 0000000..18e1f73
--- /dev/null
+++ b/phar-stub.php
@@ -0,0 +1,17 @@
+<?php
+
+require_once 'vendor/autoload.php';
+
+// The following was taken from Guzzle (MIT license)
+
+// Copy the cacert.pem file from the phar if it is not in the temp folder.
+$from = 'phar://geoip2.phar/vendor/guzzle/guzzle/src/Guzzle/Http/Resources/cacert.pem';
+$certFile = sys_get_temp_dir() . '/guzzle-cacert.pem';
+
+// Only copy when the file size is different
+if (!file_exists($certFile) || filesize($certFile) != filesize($from)) {
+    if (!copy($from, $certFile)) {
+        throw new RuntimeException("Could not copy {$from} to {$certFile}: "
+            . var_export(error_get_last(), true));
+    }
+}