diff --git a/modules/member/member.admin.controller.php b/modules/member/member.admin.controller.php
index e64f41b29..38fe30eb8 100644
--- a/modules/member/member.admin.controller.php
+++ b/modules/member/member.admin.controller.php
@@ -626,13 +626,21 @@ class MemberAdminController extends Member
 		$this->setRedirectUrl($returnUrl);
 	}
 
-	function createSignupForm($identifier)
+	public static function createSignupForm($config)
 	{
-		global $lang;
-		$oMemberModel = getModel('member');
+		// Maintain backward compatibility with inconsistent use of the first parameter of this method.
+		if (is_object($config))
+		{
+			$identifier = $config->identifier ?? 'user_id';
+		}
+		else
+		{
+			$identifier = strval($config) ?: 'user_id';
+			$config = new \stdClass;
+		}
 
 		// Get join form list which is additionally set
-		$extendItems = $oMemberModel->getJoinFormList();
+		$extendItems = MemberModel::getJoinFormList();
 
 		$items = array('user_id', 'email_address', 'phone_number', 'password', 'user_name', 'nick_name', 'homepage', 'blog', 'birthday', 'signature', 'profile_image', 'image_name', 'image_mark');
 		$mustRequireds = array('email_address', 'nick_name', 'password');
@@ -642,7 +650,6 @@ class MemberAdminController extends Member
 
 		foreach($items as $key)
 		{
-			unset($signupItem);
 			$signupItem = new stdClass;
 			$signupItem->isDefaultForm = true;
 			$signupItem->name = $key;
diff --git a/modules/member/member.class.php b/modules/member/member.class.php
index 84ad7b134..3b2c30171 100644
--- a/modules/member/member.class.php
+++ b/modules/member/member.class.php
@@ -367,20 +367,26 @@ class Member extends ModuleObject
 
 		// Check signup form
 		$oModuleController = getController('module');
-		$oMemberAdminController = getAdminController('member');
 		if(empty($config->identifier))
 		{
 			$config->identifier = 'user_id';
+			$changed = true;
 		}
 		if(empty($config->identifiers))
 		{
 			$config->identifiers = array('user_id', 'email_address');
+			$changed = true;
 		}
 		if(empty($config->signupForm) || !is_array($config->signupForm))
 		{
-			$config->signupForm = $oMemberAdminController->createSignupForm($config);
-			$output = $oModuleController->updateModuleConfig('member', $config);
+			$config->signupForm = MemberAdminController::createSignupForm($config);
+			$changed = true;
 		}
+		if($changed)
+		{
+			$oModuleController->updateModuleConfig('member', $config);
+		}
+
 		$phone_found = false;
 		foreach($config->signupForm as $no => $signupItem)
 		{
@@ -443,7 +449,7 @@ class Member extends ModuleObject
 		// Save updated config
 		if($changed)
 		{
-			$output = $oModuleController->updateModuleConfig('member', $config);
+			$oModuleController->updateModuleConfig('member', $config);
 		}
 
 		// Check skin
diff --git a/modules/member/member.model.php b/modules/member/member.model.php
index 92a153fc0..a85326922 100644
--- a/modules/member/member.model.php
+++ b/modules/member/member.model.php
@@ -128,7 +128,7 @@ class MemberModel extends Member
 		// Set signup form
 		if(!isset($config->signupForm) || !is_array($config->signupForm))
 		{
-			$config->signupForm = getAdminController('member')->createSignupForm($config->identifier);
+			$config->signupForm = MemberAdminController::createSignupForm($config);
 		}
 		foreach($config->signupForm as $key => $value)
 		{