diff --git a/docs/src/features/monte_carlo.md b/docs/src/features/monte_carlo.md
index 6f59d165df..6aaadb9e6b 100644
--- a/docs/src/features/monte_carlo.md
+++ b/docs/src/features/monte_carlo.md
@@ -288,8 +288,7 @@ and use that for calculating the trajectory:
 
 ```julia
 function prob_func(prob,i,repeat)
-  prob.u0 = rand()*prob.u0
-  prob
+  ODEProblem(prob.f,rand()*prob.u0,prob.tspan)
 end
 ```
 
@@ -431,8 +430,7 @@ Our `prob_func` will simply randomize the initial condition:
 prob = ODEProblem((t,u)->1.01u,0.5,(0.0,1.0))
 
 function prob_func(prob,i,repeat)
-  prob.u0 = rand()*prob.u0
-  prob
+  ODEProblem(prob.f,rand()*prob.u0,prob.tspan)
 end
 ```