diff --git a/src/model/solve.jl b/src/model/solve.jl
index d517c12..fb92e23 100644
--- a/src/model/solve.jl
+++ b/src/model/solve.jl
@@ -28,23 +28,34 @@ end
 function solve(
     instance::Instance;
     optimizer = nothing,
+    lp_optimizer = nothing,
     output = nothing,
     marginal_costs = true,
     return_model = false,
 )
 
-    milp_optimizer = lp_optimizer = optimizer
+    if lp_optimizer == nothing
+        if optimizer == nothing
+            # If neither is provided, use default LP optimizer.
+            lp_optimizer = _get_default_lp_optimizer()
+        else
+            # If only MIP optimizer is provided, use it as
+            # LP solver too.
+            lp_optimizer = optimizer 
+        end
+    end
+
     if optimizer == nothing
-        milp_optimizer = _get_default_milp_optimizer()
-        lp_optimizer = _get_default_lp_optimizer()
+        optimizer = _get_default_milp_optimizer()
     end
 
+
     @info "Building graph..."
     graph = RELOG.build_graph(instance)
     _print_graph_stats(instance, graph)
 
     @info "Building optimization model..."
-    model = RELOG.build_model(instance, graph, milp_optimizer)
+    model = RELOG.build_model(instance, graph, optimizer)
 
     @info "Optimizing MILP..."
     JuMP.optimize!(model)
diff --git a/src/web/run.jl b/src/web/run.jl
index e490c59..cd1a23e 100644
--- a/src/web/run.jl
+++ b/src/web/run.jl
@@ -2,6 +2,7 @@ println("Initializing...")
 
 using Logging
 using Cbc
+using Clp
 using JSON
 using JuMP
 using RELOG
@@ -15,8 +16,9 @@ function solve(root, filename)
     ref_solution, ref_model = RELOG.solve(
         ref_file,
         optimizer=optimizer,
+        lp_optimizer=Clp.Optimizer,
         return_model=true,
-        marginal_costs=false,
+        marginal_costs=true,
     )
     Libc.flush_cstdio()
     flush(stdout)
@@ -59,6 +61,7 @@ function solve(root, filename)
             ref_model,
             scenario,
             optimizer=optimizer,
+            lp_optimizer=Clp.Optimizer,
         )
         if length(sc_solution) == 0
             return