diff --git a/src/problem_solvers.jl b/src/problem_solvers.jl
index c72bf91..e4f3e53 100644
--- a/src/problem_solvers.jl
+++ b/src/problem_solvers.jl
@@ -7,6 +7,7 @@ using ..SaveLoadUtils
 using NamedTrajectories
 using QuantumCollocationCore
 using MathOptInterface
+using Ipopt
 using TestItems
 const MOI = MathOptInterface