diff --git a/pybasicbayes/models/factor_analysis.py b/pybasicbayes/models/factor_analysis.py
index 69a0624742be8dfb58e215cb3949c3decf8a3cae..03c352bb9b37ca5fc49e2029b380ff33c0697a14 100644
--- a/pybasicbayes/models/factor_analysis.py
+++ b/pybasicbayes/models/factor_analysis.py
@@ -26,9 +26,9 @@ class FactorAnalysisStates(object):
     def __init__(self, model, data, mask=None, **kwargs):
         self.model = model
         self.X = data
-        self.mask = mask
         if mask is None:
             mask = np.ones_like(data, dtype=bool)
+        self.mask = mask
         assert data.shape == mask.shape and mask.dtype == bool
         assert self.X.shape[1] == self.D_obs