diff --git a/Project.toml b/Project.toml
index 8c4a58045e..8061f6f1ef 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "ModelingToolkit"
 uuid = "961ee093-0014-501f-94e3-6117800e7a78"
 authors = ["Yingbo Ma <mayingbo5@gmail.com>", "Chris Rackauckas <accounts@chrisrackauckas.com> and contributors"]
-version = "9.64.2"
+version = "9.64.3"
 
 [deps]
 AbstractTrees = "1520ce14-60c1-5f80-bbc7-55ef81b5835c"
@@ -190,4 +190,4 @@ Sundials = "c3572dad-4567-51f8-b174-8c6c989267f4"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["AmplNLWriter", "BenchmarkTools", "BoundaryValueDiffEqMIRK", "BoundaryValueDiffEqAscher", "ControlSystemsBase", "DataInterpolations", "DelayDiffEq", "NonlinearSolve", "ForwardDiff", "Ipopt", "Ipopt_jll", "ModelingToolkitStandardLibrary", "Optimization", "OptimizationOptimJL", "OptimizationMOI", "OrdinaryDiffEq", "OrdinaryDiffEqCore", "OrdinaryDiffEqDefault", "REPL", "Random", "ReferenceTests", "SafeTestsets", "StableRNGs", "Statistics", "SteadyStateDiffEq", "Test", "StochasticDiffEq", "Sundials", "StochasticDelayDiffEq", "Pkg", "JET", "OrdinaryDiffEqNonlinearSolve", "Logging"]
\ No newline at end of file
+test = ["AmplNLWriter", "BenchmarkTools", "BoundaryValueDiffEqMIRK", "BoundaryValueDiffEqAscher", "ControlSystemsBase", "DataInterpolations", "DelayDiffEq", "NonlinearSolve", "ForwardDiff", "Ipopt", "Ipopt_jll", "ModelingToolkitStandardLibrary", "Optimization", "OptimizationOptimJL", "OptimizationMOI", "OrdinaryDiffEq", "OrdinaryDiffEqCore", "OrdinaryDiffEqDefault", "REPL", "Random", "ReferenceTests", "SafeTestsets", "StableRNGs", "Statistics", "SteadyStateDiffEq", "Test", "StochasticDiffEq", "Sundials", "StochasticDelayDiffEq", "Pkg", "JET", "OrdinaryDiffEqNonlinearSolve", "Logging"]
diff --git a/src/systems/nonlinear/nonlinearsystem.jl b/src/systems/nonlinear/nonlinearsystem.jl
index 06e843d6be..ad3fbfdeef 100644
--- a/src/systems/nonlinear/nonlinearsystem.jl
+++ b/src/systems/nonlinear/nonlinearsystem.jl
@@ -792,7 +792,8 @@ function SciMLBase.SCCNonlinearProblem{iip}(sys::NonlinearSystem, u0map,
     new_eqs = eqs[reduce(vcat, eq_sccs)]
     @set! sys.unknowns = new_dvs
     @set! sys.eqs = new_eqs
-    sys = complete(sys)
+    @set! sys.index_cache = subset_unknowns_observed(
+        get_index_cache(sys), sys, new_dvs, getproperty.(obs, (:lhs,)))
     return SCCNonlinearProblem(subprobs, explicitfuns, p, true; sys)
 end
 
diff --git a/test/scc_nonlinear_problem.jl b/test/scc_nonlinear_problem.jl
index ef4638cdb0..92030a84aa 100644
--- a/test/scc_nonlinear_problem.jl
+++ b/test/scc_nonlinear_problem.jl
@@ -263,3 +263,22 @@ end
     sol = solve(prob, NewtonRaphson())
     @test SciMLBase.successful_retcode(sol)
 end
+
+@testset "SCCNonlinearProblem retains parameter order" begin
+    @variables x y z
+    @parameters σ β ρ
+    @mtkbuild fullsys = NonlinearSystem(
+        [0 ~ x^3 * β + y^3 * ρ - σ, 0 ~ x^2 + 2x * y + y^2, 0 ~ z^2 - 4z + 4],
+        [x, y, z], [σ, β, ρ])
+
+    u0 = [x => 1.0,
+        y => 0.0,
+        z => 0.0]
+
+    p = [σ => 28.0,
+        ρ => 10.0,
+        β => 8 / 3]
+
+    sccprob = SCCNonlinearProblem(fullsys, u0, p)
+    @test isequal(parameters(fullsys), parameters(sccprob.f.sys))
+end