diff --git a/lib/behat/classes/behat_command.php b/lib/behat/classes/behat_command.php
index 9c0d6839388..ed309f057cb 100644
--- a/lib/behat/classes/behat_command.php
+++ b/lib/behat/classes/behat_command.php
@@ -157,7 +157,7 @@ class behat_command {
 
             // Returning composer error code to avoid conflicts with behat and moodle error codes.
             self::output_msg(get_string('errorcomposer', 'tool_behat'));
-            return BEHAT_EXITCODE_COMPOSER;
+            return TESTING_EXITCODE_COMPOSER;
         }
 
         // Behat test command.
@@ -167,7 +167,7 @@ class behat_command {
 
             // Returning composer error code to avoid conflicts with behat and moodle error codes.
             self::output_msg(get_string('errorbehatcommand', 'tool_behat', self::get_behat_command()));
-            return BEHAT_EXITCODE_COMPOSER;
+            return TESTING_EXITCODE_COMPOSER;
         }
 
         // No empty values.
diff --git a/lib/behat/lib.php b/lib/behat/lib.php
index 7a422ed9c24..d80486ec4dd 100644
--- a/lib/behat/lib.php
+++ b/lib/behat/lib.php
@@ -38,7 +38,6 @@ define('BEHAT_EXITCODE_REQUIREMENT', 251);
 define('BEHAT_EXITCODE_PERMISSIONS', 252);
 define('BEHAT_EXITCODE_REINSTALL', 253);
 define('BEHAT_EXITCODE_INSTALL', 254);
-define('BEHAT_EXITCODE_COMPOSER', 255);
 define('BEHAT_EXITCODE_INSTALLED', 256);
 
 /**
@@ -458,4 +457,4 @@ function cli_execute_parallel($cmds, $cwd = null) {
         }
     }
     return $processes;
-}
\ No newline at end of file
+}
diff --git a/lib/testing/lib.php b/lib/testing/lib.php
index de9db16bca6..bfe0c303c0d 100644
--- a/lib/testing/lib.php
+++ b/lib/testing/lib.php
@@ -25,6 +25,13 @@
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 
+/**
+ * Composer error exit status.
+ *
+ * @var integer
+ */
+define('TESTING_EXITCODE_COMPOSER', 255);
+
 /**
  * Returns relative path against current working directory,
  * to be used for shell execution hints.
@@ -170,22 +177,45 @@ function testing_error($errorcode, $text = '') {
  * @return void exit() if something goes wrong
  */
 function testing_update_composer_dependencies() {
-
     // To restore the value after finishing.
     $cwd = getcwd();
 
-    // Dirroot.
-    chdir(__DIR__ . '/../..');
+    // Set some paths.
+    $dirroot = dirname(dirname(__DIR__));
+    $composerpath = $dirroot . DIRECTORY_SEPARATOR . 'composer.phar';
+    $composerurl = 'https://getcomposer.org/composer.phar';
 
-    // Download composer.phar if we can.
-    if (!file_exists(__DIR__ . '/../../composer.phar')) {
-        passthru("curl http://getcomposer.org/installer | php", $code);
-        if ($code != 0) {
-            exit($code);
+    // Switch to Moodle's dirroot for easier path handling.
+    chdir($dirroot);
+
+    // Download or update composer.phar. Unfortunately we can't use the curl
+    // class in filelib.php as we're running within one of the test platforms.
+    if (!file_exists($composerpath)) {
+        $file = @fopen($composerpath, 'w+');
+        if ($file === false) {
+            $errordetails = error_get_last();
+            $error = sprintf("Unable to open composer.phar\nPHP error: %s",
+                             $errordetails['message']);
+            testing_error(TESTING_EXITCODE_COMPOSER, $error);
+        }
+        $curl = curl_init();
+
+        curl_setopt($curl, CURLOPT_URL,  $composerurl);
+        curl_setopt($curl, CURLOPT_FILE, $file);
+        $result = curl_exec($curl);
+
+        $curlerrno = curl_errno($curl);
+        $curlerror = curl_error($curl);
+
+        curl_close($curl);
+        fclose($file);
+
+        if (!$result) {
+            $error = sprintf("Unable to download composer.phar\ncURL error (%d): %s",
+                             $curlerrno, $curlerror);
+            testing_error(TESTING_EXITCODE_COMPOSER, $error);
         }
     } else {
-
-        // If it is already there update the installer.
         passthru("php composer.phar self-update", $code);
         if ($code != 0) {
             exit($code);
@@ -198,5 +228,6 @@ function testing_update_composer_dependencies() {
         exit($code);
     }
 
+    // Return to our original location.
     chdir($cwd);
 }