diff --git a/pytential/qbx/__init__.py b/pytential/qbx/__init__.py
index b3bb102f66416aa34eb8f3867de4edd8a409ba66..869f92220f16817478375da3001e79f3c512b956 100644
--- a/pytential/qbx/__init__.py
+++ b/pytential/qbx/__init__.py
@@ -951,8 +951,8 @@ class QBXLayerPotentialSource(LayerPotentialSourceBase):
 
 
 __all__ = (
-        QBXLayerPotentialSource,
-        QBXTargetAssociationFailedException,
+        "QBXLayerPotentialSource",
+        "QBXTargetAssociationFailedException",
         )
 
 # vim: fdm=marker
diff --git a/pytential/unregularized.py b/pytential/unregularized.py
index a2fe4ad0ad6e941642a524c4e594718f1412c0b3..b0d9926a4b8aedc7fb14a8ab4fe1531aeff743f9 100644
--- a/pytential/unregularized.py
+++ b/pytential/unregularized.py
@@ -447,7 +447,7 @@ class _FMMGeometryData(object):
 
 
 __all__ = (
-        UnregularizedLayerPotentialSource,
+        "UnregularizedLayerPotentialSource",
         )
 
 # vim: fdm=marker