diff --git a/sklift/models/__init__.py b/sklift/models/__init__.py
index 81290fe..7cb5b39 100644
--- a/sklift/models/__init__.py
+++ b/sklift/models/__init__.py
@@ -1,3 +1,3 @@
 from .models import SoloModel, ClassTransformation, ClassTransformationReg, TwoModels
 
-__all__ = [SoloModel, ClassTransformation, ClassTransformationReg, TwoModels]
+__all__ = ['SoloModel', 'ClassTransformation', 'ClassTransformationReg', 'TwoModels']