diff --git a/authentication/source/java/ch/systemsx/cisd/authentication/ldap/LDAPPrincipalQuery.java b/authentication/source/java/ch/systemsx/cisd/authentication/ldap/LDAPPrincipalQuery.java
index ecdeae050448c88f61a7b0ab53ed77eb9524f420..dce29c12071ce4c5213be3b8418472c6ef66e0b9 100644
--- a/authentication/source/java/ch/systemsx/cisd/authentication/ldap/LDAPPrincipalQuery.java
+++ b/authentication/source/java/ch/systemsx/cisd/authentication/ldap/LDAPPrincipalQuery.java
@@ -271,6 +271,7 @@ public final class LDAPPrincipalQuery implements ISelfTestable
      *            usually a big performance boost.
      * @return The list of principals matching the query
      */
+    @SuppressWarnings("null")
     public List<Principal> listPrincipalsByKeyValue(String key, String value,
             Collection<String> additionalAttributesOrNull, int limit)
     {
@@ -372,6 +373,7 @@ public final class LDAPPrincipalQuery implements ISelfTestable
                 config.getSecurityPrincipalPassword(), true);
     }
 
+    @SuppressWarnings("null")
     private DirContext createContextForDistinguishedName(String dn, String password,
             boolean useThreadContext) throws NamingException
     {