diff --git a/src/solver.jl b/src/solver.jl
index 259b5d8..3910c8f 100644
--- a/src/solver.jl
+++ b/src/solver.jl
@@ -1,5 +1,6 @@
 using DifferentialEquations
 using Random
+include("constants.jl")
 using .Constants
 
 """