diff --git a/source4/dsdb/samdb/ldb_modules/tests/samba3sam.py b/source4/dsdb/samdb/ldb_modules/tests/samba3sam.py
index 8d4047b0b8c..78b7eca0773 100644
--- a/source4/dsdb/samdb/ldb_modules/tests/samba3sam.py
+++ b/source4/dsdb/samdb/ldb_modules/tests/samba3sam.py
@@ -61,6 +61,7 @@ class MapBaseTestCase(TestCaseInTempDir):
 
     def setUp(self):
         cmdline_loadparm.set("sid generator", "backend")
+        cmdline_loadparm.set("workgroup", "TESTS")
         super(MapBaseTestCase, self).setUp()
 
         def make_dn(basedn, rdn):