diff --git a/appinfo/routes.php b/appinfo/routes.php
index 3676ca5..63e5ca9 100644
--- a/appinfo/routes.php
+++ b/appinfo/routes.php
@@ -48,6 +48,12 @@ return [
 			'url' => '/saml/sls',
 			'verb' => 'GET',
 		],
+		[
+			'name' => 'SAML#singleLogoutService',
+			'url' => '/saml/sls',
+			'verb' => 'POST',
+			'postfix' => 'slspost',
+		],
 		[
 			'name' => 'SAML#notProvisioned',
 			'url' => '/saml/notProvisioned',
diff --git a/lib/Controller/SAMLController.php b/lib/Controller/SAMLController.php
index 50bec66..e289840 100644
--- a/lib/Controller/SAMLController.php
+++ b/lib/Controller/SAMLController.php
@@ -319,6 +319,13 @@ class SAMLController extends Controller {
 	public function singleLogoutService() {
 		$isFromGS = ($this->config->getSystemValue('gs.enabled', false) &&
 					 $this->config->getSystemValue('gss.mode', '') === 'master');
+
+		// Some IDPs send the SLO request via POST, but OneLogin php-saml only handles GET.
+		// To hack around this issue we copy the request from _POST to _GET.
+		if(!empty($_POST['SAMLRequest'])) {
+			$_GET['SAMLRequest'] = $_POST['SAMLRequest'];
+		}
+
 		$isFromIDP = !$isFromGS && !empty($_GET['SAMLRequest']);
 
 		if($isFromIDP) {
diff --git a/tests/unit/AppInfo/RoutesTest.php b/tests/unit/AppInfo/RoutesTest.php
index e806fa9..b8e71b0 100644
--- a/tests/unit/AppInfo/RoutesTest.php
+++ b/tests/unit/AppInfo/RoutesTest.php
@@ -54,6 +54,12 @@ class Test extends TestCase  {
 					'url' => '/saml/sls',
 					'verb' => 'GET',
 				],
+				[
+					'name' => 'SAML#singleLogoutService',
+					'url' => '/saml/sls',
+					'verb' => 'POST',
+					'postfix' => 'slspost',
+				],
 				[
 					'name' => 'SAML#notProvisioned',
 					'url' => '/saml/notProvisioned',