diff --git a/zipline/lines.py b/zipline/lines.py
index 1c3a558f..d31c47d6 100644
--- a/zipline/lines.py
+++ b/zipline/lines.py
@@ -172,6 +172,8 @@ class SimulatedTrading(object):
 
     def close(self):
         log.info("Closing Simulation: {id}".format(id=self.sim_id))
+        if self.results_socket:
+            self.results_socket.close()
         if self.proc and self.send_sighup:
             ppid = os.getppid()
             if self.success: