diff --git a/lib/spack/spack/test/modules.py b/lib/spack/spack/test/modules.py
index d76e0cd054c..098777c48b2 100644
--- a/lib/spack/spack/test/modules.py
+++ b/lib/spack/spack/test/modules.py
@@ -84,7 +84,8 @@ def mock_open(filename, mode):
 configuration_blacklist = {
     'enable': ['tcl'],
     'tcl': {
-        'blacklist': ['callpath'],
+        'whitelist': ['zmpi'],
+        'blacklist': ['callpath', 'mpi'],
         'all': {
             'autoload': 'direct'
         }
@@ -207,6 +208,7 @@ def test_blacklist(self):
         spack.modules.CONFIGURATION = configuration_blacklist
         spec = spack.spec.Spec('mpileaks arch=x86-linux')
         content = self.get_modulefile_content(spec)
+        print('\n'.join(content))
         self.assertEqual(len([x for x in content if 'is-loaded' in x]), 1)
         self.assertEqual(len([x for x in content if 'module load ' in x]), 1)