diff --git a/lib/OptimizationMOI/src/OptimizationMOI.jl b/lib/OptimizationMOI/src/OptimizationMOI.jl
index 06b48882f..1f3d3a66d 100644
--- a/lib/OptimizationMOI/src/OptimizationMOI.jl
+++ b/lib/OptimizationMOI/src/OptimizationMOI.jl
@@ -116,25 +116,25 @@ function __moi_status_to_ReturnCode(status::MOI.TerminationStatusCode)
     end
 end
 
-function get_expr_map(prob, f)
-    pairs_arr = if prob.p isa SciMLBase.NullParameters
-        [Meta.parse(string(_s)) => Expr(:ref, :x, i) for (i, _s) in enumerate(f.syms)]
-    else
-        vcat([Symbol(_s) => Expr(:ref, :x, i) for (i, _s) in enumerate(f.syms)],
-        [Symbol(_s) => Expr(:ref, p, i) for (i, _p) in enumerate(f.paramsyms)])
-    end
-    return pairs_arr
-end
+# function get_expr_map(prob, f)
+#     pairs_arr = if prob.p isa SciMLBase.NullParameters
+#         [Meta.parse(string(_s)) => Expr(:ref, :x, i) for (i, _s) in enumerate(f.syms)]
+#     else
+#         vcat([Symbol(_s) => Expr(:ref, :x, i) for (i, _s) in enumerate(f.syms)],
+#         [Symbol(_s) => Expr(:ref, p, i) for (i, _p) in enumerate(f.paramsyms)])
+#     end
+#     return pairs_arr
+# end
 
-"""
-Substitute variables and parameters with canonical names x and p respectively.
-"""
-function rep_pars_vals!(e::Expr, p)
-    rep_pars_vals!.(e.args, Ref(p))
-    replace!(e.args, p...)
-end
+# """
+# Substitute variables and parameters with canonical names x and p respectively.
+# """
+# function rep_pars_vals!(e::Expr, p)
+#     rep_pars_vals!.(e.args, Ref(p))
+#     replace!(e.args, p...)
+# end
 
-function rep_pars_vals!(e, p) end
+# function rep_pars_vals!(e, p) end
 
 """
 Replaces every expression `:x[i]` with `:x[MOI.VariableIndex(i)]`
diff --git a/lib/OptimizationMOI/src/moi.jl b/lib/OptimizationMOI/src/moi.jl
index 457ab49be..f6414ac54 100644
--- a/lib/OptimizationMOI/src/moi.jl
+++ b/lib/OptimizationMOI/src/moi.jl
@@ -23,8 +23,9 @@ function MOIOptimizationCache(prob::OptimizationProblem, opt; kwargs...)
             throw(ArgumentError("Expected an `OptimizationProblem` that was setup via an `OptimizationSystem`, or AutoModelingToolkit ad choice"))
         end
     end
+
     # TODO: check if the problem is at most bilinear, i.e. affine and or quadratic terms in two variables
-    expr_map = get_expr_map(prob, f)
+    expr_map = get_expr_map(prob.f.sys)
     expr = repl_getindex!(convert_to_expr(f.expr, expr_map; expand_expr = false))
 
     cons = MTK.constraints(f.sys)
@@ -448,3 +449,12 @@ function convert_to_expr(eq, expr_map; expand_expr = false)
     expr = symbolify!(expr)
     return expr
 end
+
+function get_expr_map(sys)
+    dvs = ModelingToolkit.states(sys)
+    ps = ModelingToolkit.parameters(sys)
+    return vcat([ModelingToolkit.toexpr(_s) => Expr(:ref, :x, i)
+                 for (i, _s) in enumerate(dvs)],
+        [ModelingToolkit.toexpr(_p) => Expr(:ref, :p, i)
+         for (i, _p) in enumerate(ps)])
+end
\ No newline at end of file