diff --git a/msmbuilder/preprocessing/timeseries.py b/msmbuilder/preprocessing/timeseries.py
index b6da7260..3ba48e2b 100644
--- a/msmbuilder/preprocessing/timeseries.py
+++ b/msmbuilder/preprocessing/timeseries.py
@@ -97,13 +97,13 @@ def __init__(self, com=None, span=None, halflife=None, min_periods=0,
         self.min_periods = min_periods
         self.freq = freq
         self.adjust = adjust
-
+    # freq removed in Pandas>=0.23
     def _ewma(self, sequence):
         ewma = DataFrame(sequence).ewm(com=self.com,
                                        span=self.span,
                                        halflife=self.halflife,
                                        min_periods=self.min_periods,
-                                       freq=self.freq,
+                                       ##### freq=self.freq,
                                        adjust=self.adjust).mean()
 
         return ewma.values