diff --git a/apps/user_ldap/lib/Access.php b/apps/user_ldap/lib/Access.php
index 389d876719bb8..3730ea3aaa939 100644
--- a/apps/user_ldap/lib/Access.php
+++ b/apps/user_ldap/lib/Access.php
@@ -502,15 +502,15 @@ public function dn2ocname($fdn, $ldapName = null, $isUser = true, &$newlyMapped
 		}
 
 		if ($isUser) {
-			$nameAttribute = $this->connection->ldapUserDisplayName;
+			$nameAttribute = strtolower($this->connection->ldapUserDisplayName);
 			$filter = $this->connection->ldapUserFilter;
 			$uuidAttr = 'ldapUuidUserAttribute';
 			$uuidOverride = $this->connection->ldapExpertUUIDUserAttr;
-			$usernameAttribute = (string)$this->connection->ldapExpertUsernameAttr;
+			$usernameAttribute = strtolower($this->connection->ldapExpertUsernameAttr);
 			$attributesToRead = [$nameAttribute,$usernameAttribute];
 			// TODO fetch also display name attributes and cache them if the user is mapped
 		} else {
-			$nameAttribute = $this->connection->ldapGroupDisplayName;
+			$nameAttribute = strtolower($this->connection->ldapGroupDisplayName);
 			$filter = $this->connection->ldapGroupFilter;
 			$uuidAttr = 'ldapUuidGroupAttribute';
 			$uuidOverride = $this->connection->ldapExpertUUIDGroupAttr;
diff --git a/apps/user_ldap/tests/AccessTest.php b/apps/user_ldap/tests/AccessTest.php
index 941aa51fc3122..ff2eda99abfad 100644
--- a/apps/user_ldap/tests/AccessTest.php
+++ b/apps/user_ldap/tests/AccessTest.php
@@ -612,7 +612,8 @@ public function testFetchListOfUsers() {
 
 		$this->prepareMocksForSearchTests($base, $fakeConnection, $fakeSearchResultResource, $fakeLdapEntries);
 
-		$this->connection->expects($this->exactly($fakeLdapEntries['count']))
+		// Called twice per user, for userExists and userExistsOnLdap
+		$this->connection->expects($this->exactly(2 * $fakeLdapEntries['count']))
 			->method('writeToCache')
 			->with($this->stringStartsWith('userExists'), true);