diff --git a/application/logindefault.class.inc.php b/application/logindefault.class.inc.php
index 85f8e4609..508a2623e 100644
--- a/application/logindefault.class.inc.php
+++ b/application/logindefault.class.inc.php
@@ -35,8 +35,6 @@ class LoginDefaultBefore extends AbstractLoginFSMExtension
 		if ($index !== false) {
 			// Force login mode
 			Session::Set('login_mode', $sProposedLoginMode);
-		} elseif (!Session::IsSet('login_mode')) {
-			Session::Unset('login_mode');
 		}
 		return LoginWebPage::LOGIN_FSM_CONTINUE;
 	}
diff --git a/tests/php-unit-tests/unitary-tests/application/LoginDefaultBeforeTest.php b/tests/php-unit-tests/unitary-tests/application/LoginDefaultBeforeTest.php
new file mode 100644
index 000000000..96c05d46e
--- /dev/null
+++ b/tests/php-unit-tests/unitary-tests/application/LoginDefaultBeforeTest.php
@@ -0,0 +1,69 @@
+<?php
+
+use Combodo\iTop\Application\Helper\Session;
+use Combodo\iTop\Test\UnitTest\ItopDataTestCase;
+
+/**
+ * @runClassInSeparateProcess Required because PHPUnit outputs something earlier, thus causing the headers to be sent
+ */
+class LoginDefaultBeforeTest extends ItopDataTestCase
+{
+	protected function setUp(): void
+	{
+		parent::setUp();
+		Session::$bAllowCLI = true;
+		Session::Start();
+		$_REQUEST = [];
+		$this->RequireOnceItopFile('application/logindefault.class.inc.php');
+	}
+
+	protected function tearDown(): void
+	{
+		parent::tearDown();
+		Session::$bAllowCLI = false;
+	}
+
+	public function testOnStart_NoLoginModeRequiredNorStoredInSession()
+	{
+		$this->CallStartAndCheckLoginModeStored(null, null);
+	}
+
+	public function testOnStart_StoreLoginModeRequiredWhenConfigured()
+	{
+		MetaModel::GetConfig()->SetAllowedLoginTypes(["SAML"]);
+		$_REQUEST['login_mode'] = "SAML";
+
+		$this->CallStartAndCheckLoginModeStored("SAML", null);
+	}
+
+	public function testOnStart_SwitchLoginModeWhenNewOneRequiredIsConfigured()
+	{
+		MetaModel::GetConfig()->SetAllowedLoginTypes(["SAML"]);
+		$_REQUEST['login_mode'] = "SAML";
+
+		$this->CallStartAndCheckLoginModeStored("SAML");
+	}
+
+	public function testOnStart_PreserveCurrentLoginModeInSessionWhenNewOneRequiredIsNotConfigured()
+	{
+		$_REQUEST['login_mode'] = "SAML";
+
+		$this->CallStartAndCheckLoginModeStored("previous_mode");
+	}
+
+	public function testOnStart_PreserveCurrentLoginModeInSessionWhenNoOtherRequired()
+	{
+		$this->CallStartAndCheckLoginModeStored('previous_mode');
+	}
+
+	private function CallStartAndCheckLoginModeStored($expected, ?string $sPreviousLoginMode = 'previous_mode')
+	{
+		Session::Set('login_mode', $sPreviousLoginMode);
+
+		$iErrorCode = 666;
+		$res  = $this->InvokeNonPublicMethod(LoginDefaultBefore::class, 'OnStart', new LoginDefaultBefore(), [&$iErrorCode]);
+		$this->assertEquals(LoginWebPage::EXIT_CODE_OK, $iErrorCode);
+		$this->assertEquals(LoginWebPage::LOGIN_FSM_CONTINUE, $res);
+		$this->assertEquals($expected, Session::Get('login_mode'));
+	}
+}