diff --git a/tests/test_transforms.py b/tests/test_transforms.py
index 7d3b7aa9..d61a9cf2 100644
--- a/tests/test_transforms.py
+++ b/tests/test_transforms.py
@@ -344,8 +344,8 @@ class TestTALIB(TestCase):
                 # factory.create_test_panel_ohlc_source(self.sim_params)
 
     def test_multiple_talib_with_args(self):
-        zipline_transforms = [ta.MA(window_length=10),
-                              ta.MA(window_length=25)]
+        zipline_transforms = [ta.MA(timeperiod=10),
+                              ta.MA(timeperiod=25)]
         talib_fn = talib.abstract.MA
         algo = TALIBAlgorithm(talib=zipline_transforms)
         algo.run(self.source)
diff --git a/zipline/transforms/ta.py b/zipline/transforms/ta.py
index 700b6758..09292680 100644
--- a/zipline/transforms/ta.py
+++ b/zipline/transforms/ta.py
@@ -94,10 +94,10 @@ def make_transform(talib_fn, name):
                        'volume': volume,
                        'close': close}
 
-            # Rename window_length to timeperiod to conform with
-            # external batch_transform interface.
-            if 'window_length' in kwargs:
-                kwargs['timeperiod'] = kwargs['window_length']
+            # Rename timeperiod to window_length to conform with
+            # TALib interface.
+            if 'timeperiod' in kwargs:
+                kwargs['window_length'] = kwargs['timeperiod']
 
             self.call_kwargs = kwargs