diff --git a/tupak/waveform_generator.py b/tupak/waveform_generator.py
index 30667d84050c34500034fbd736ceb6c49fce8f88..7ffb7c84e394514addd5d49eb7325c6b63a1538b 100644
--- a/tupak/waveform_generator.py
+++ b/tupak/waveform_generator.py
@@ -89,7 +89,7 @@ class WaveformGenerator(object):
         if self.parameter_conversion is not None:
             for key in added_keys:
                 self.parameters.pop(key)
-        return model_time_series[key]
+        return model_time_series
 
     @property
     def frequency_array(self):