diff --git a/zipline/gens/tradesimulation.py b/zipline/gens/tradesimulation.py
index 39bb0a95..101fdf34 100644
--- a/zipline/gens/tradesimulation.py
+++ b/zipline/gens/tradesimulation.py
@@ -51,7 +51,6 @@ class AlgorithmSimulator(object):
         # Algo Setup
         # ==============
         self.algo = algo
-        self.algo_start = normalize_date(self.sim_params.first_open)
 
         # ==============
         # Snapshot Setup
@@ -64,7 +63,6 @@ class AlgorithmSimulator(object):
         # We don't have a datetime for the current snapshot until we
         # receive a message.
         self.simulation_dt = None
-        self.previous_dt = self.algo_start
 
         self.clock = clock