diff --git a/GPyOpt/methods/bayesian_optimization.py b/GPyOpt/methods/bayesian_optimization.py
index c3ad58bc4..f914247b8 100644
--- a/GPyOpt/methods/bayesian_optimization.py
+++ b/GPyOpt/methods/bayesian_optimization.py
@@ -103,7 +103,7 @@ def __init__(self, f, domain = None, constraints = None, cost_withGradients = No
         self.num_cores = num_cores
         if f is not None:
             self.f = self._sign(f)
-            self.objective = SingleObjective(self.f, self.batch_size,self.objective_name)
+            self.objective = SingleObjective(self.f, self.num_cores,self.objective_name)
         else:
             self.f = None
             self.objective = None