diff --git a/btb/tuning/hyperparams/categorical.py b/btb/tuning/hyperparams/categorical.py
index 2b1c012..4bd3d51 100644
--- a/btb/tuning/hyperparams/categorical.py
+++ b/btb/tuning/hyperparams/categorical.py
@@ -49,7 +49,7 @@ def __init__(self, choices, default=NO_DEFAULT):
         self.dimensions = len(choices)
         self.cardinality = self.dimensions
         choices = np.array(choices, dtype='object')
-        self._encoder = OneHotEncoder(categories=[choices], sparse=False)
+        self._encoder = OneHotEncoder(categories=[choices], sparse_output=False)
         self._encoder.fit(choices.reshape(-1, 1))
 
     def _within_hyperparam_space(self, values):