diff --git a/ggplot/stats/smoothers.py b/ggplot/stats/smoothers.py
index 5a8fbf37..2198a3f8 100644
--- a/ggplot/stats/smoothers.py
+++ b/ggplot/stats/smoothers.py
@@ -1,7 +1,7 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 import numpy as np
-from pandas.lib import Timestamp
+from pandas import Timestamp
 import pandas as pd
 import statsmodels.api as sm
 from statsmodels.nonparametric.smoothers_lowess import lowess as smlowess
@@ -11,7 +11,7 @@
 import datetime
 
 date_types = (
-    pd.tslib.Timestamp,
+    pd.Timestamp,
     pd.DatetimeIndex,
     pd.Period,
     pd.PeriodIndex,
diff --git a/ggplot/stats/stat_smooth.py b/ggplot/stats/stat_smooth.py
index 2264a6aa..5611438d 100644
--- a/ggplot/stats/stat_smooth.py
+++ b/ggplot/stats/stat_smooth.py
@@ -55,8 +55,6 @@ class stat_smooth(geom):
     def plot(self, ax, data, _aes):
         (data, _aes) = self._update_data(data, _aes)
         variables = _aes.data
-        data = data[list(variables.values())]
-        data = data.dropna()
         x = data[variables['x']]
         y = data[variables['y']]
 
@@ -76,10 +74,7 @@ def plot(self, ax, data, _aes):
             x, y, y1, y2 = smoothers.lowess(x, y, span=span)
 
         smoothed_data = pd.DataFrame(dict(x=x, y=y, y1=y1, y2=y2))
-        try:  # change in Pandas-0.19
-            smoothed_data = smoothed_data.sort_values(by='x')
-        except:  # before Pandas-0.19
-            smoothed_data = smoothed_data.sort('x')
+        smoothed_data = smoothed_data.sort('x')
 
         params = self._get_plot_args(data, _aes)
         if 'alpha' not in params:
diff --git a/ggplot/themes/theme_538.py b/ggplot/themes/theme_538.py
index d9182f25..20452837 100644
--- a/ggplot/themes/theme_538.py
+++ b/ggplot/themes/theme_538.py
@@ -1,8 +1,6 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
-from cycler import cycler
 from .theme import theme_base
-from cycler import cycler
 
 class theme_538(theme_base):
     """
diff --git a/ggplot/utils.py b/ggplot/utils.py
index d0d5dfb6..6c9a92f7 100644
--- a/ggplot/utils.py
+++ b/ggplot/utils.py
@@ -78,7 +78,7 @@ def is_iterable(obj):
         return False
 
 date_types = (
-    pd.tslib.Timestamp,
+    pd.Timestamp,
     pd.DatetimeIndex,
     pd.Period,
     pd.PeriodIndex,