diff --git a/src/parameter_indexing.jl b/src/parameter_indexing.jl
index 12fe0a5..de21a38 100644
--- a/src/parameter_indexing.jl
+++ b/src/parameter_indexing.jl
@@ -628,7 +628,8 @@ function _getp(sys, ::ArraySymbolic, ::SymbolicTypeTrait, p)
         idx = parameter_index(sys, p)
         if is_timeseries_parameter(sys, p)
             ts_idx = timeseries_parameter_index(sys, p)
-            return GetParameterTimeseriesIndex(idx, ts_idx)
+            return GetParameterTimeseriesIndex(
+                GetParameterIndex(idx), GetParameterIndex(ts_idx))
         else
             return GetParameterIndex(idx)
         end
@@ -750,5 +751,5 @@ function _setp_oop(indp, ::ArraySymbolic, ::SymbolicTypeTrait, sym)
     if is_parameter(indp, sym)
         return OOPSetter(_root_indp(indp), parameter_index(indp, sym), false)
     end
-    error("$sym is not a valid parameter")
+    return setp_oop(indp, collect(sym))
 end
diff --git a/src/state_indexing.jl b/src/state_indexing.jl
index 243f7f2..6e1d3d0 100644
--- a/src/state_indexing.jl
+++ b/src/state_indexing.jl
@@ -468,7 +468,7 @@ function _setsym_oop(indp, ::ArraySymbolic, ::SymbolicTypeTrait, sym)
         return setsym_oop(indp, idx)
     elseif (idx = parameter_index(indp, sym)) !== nothing
         return FullSetter(
-            nothing, OOPSetter(indp, idx isa AbstractArray ? idx : (idx,), false))
+            nothing, OOPSetter(indp, idx, false))
     end
     return setsym_oop(indp, collect(sym))
 end
diff --git a/test/downstream/Project.toml b/test/downstream/Project.toml
index 8657d46..b4c2174 100644
--- a/test/downstream/Project.toml
+++ b/test/downstream/Project.toml
@@ -6,3 +6,4 @@ Symbolics = "0c5d862f-8b57-4792-8d23-62f2024744c7"
 
 [compat]
 SymbolicUtils = "3.2"
+ModelingToolkit = "9.60"
diff --git a/test/downstream/array_indexing.jl b/test/downstream/array_indexing.jl
new file mode 100644
index 0000000..1fcf4fd
--- /dev/null
+++ b/test/downstream/array_indexing.jl
@@ -0,0 +1,58 @@
+using ModelingToolkit, SymbolicIndexingInterface
+using ModelingToolkit: t_nounits as t, D_nounits as D
+
+@variables x(t)[1:2]
+@parameters p[1:2, 1:2] q(t)[1:2] r[1:2]
+
+ev = [x[1] ~ 2.0] => [q ~ -ones(2)]
+@mtkbuild sys = ODESystem(
+    [D(x) ~ p * x + q + r], t, [x], [p, q, r...]; continuous_events = [ev])
+@test is_timeseries_parameter(sys, q)
+@test !is_timeseries_parameter(sys, p)
+@test !is_parameter(sys, r)
+@test is_parameter(sys, r[1])
+@test is_parameter(sys, r[2])
+
+prob = ODEProblem(
+    sys, [x => ones(2)], (0.0, 10.0), [p => ones(2, 2), q => ones(2), r => 2ones(2)])
+@test prob.ps[q] ≈ ones(2)
+@test prob.ps[p] ≈ ones(2, 2)
+@test prob.ps[r] ≈ 2ones(2)
+@test prob.ps[p * q] ≈ 2ones(2)
+
+@test getu(sys, p)(prob) ≈ ones(2, 2)
+@test getu(sys, r)(prob) ≈ 2ones(2)
+
+prob.ps[p] = 2ones(2, 2)
+@test prob.ps[p] ≈ 2ones(2, 2)
+prob.ps[q] = 2ones(2)
+@test prob.ps[q] ≈ 2ones(2)
+prob.ps[r] = ones(2)
+@test prob.ps[r] ≈ ones(2)
+
+setter = setp_oop(sys, p)
+newp = setter(prob, 3ones(2, 2))
+@test getp(sys, p)(newp) ≈ 3ones(2, 2)
+setter = setp_oop(sys, r)
+newp = setter(prob, 3ones(2))
+@test getp(sys, r)(newp) ≈ 3ones(2)
+
+setter = setsym_oop(sys, p)
+_, newp = setter(prob, 3ones(2, 2))
+@test getp(sys, p)(newp) ≈ 3ones(2, 2)
+setter = setsym_oop(sys, r)
+_, newp = setter(prob, 3ones(2))
+@test getp(sys, r)(newp) ≈ 3ones(2)
+
+@test prob[x] ≈ ones(2)
+prob[x] = 2ones(2)
+@test prob[x] ≈ 2ones(2)
+
+setu(sys, p)(prob, 4ones(2, 2))
+@test prob.ps[p] ≈ 4ones(2, 2)
+setu(sys, r)(prob, 4ones(2))
+@test prob.ps[r] ≈ 4ones(2)
+
+setter = setsym_oop(sys, x)
+newu, newp = setter(prob, 3ones(2))
+@test getu(sys, x)(newu) ≈ 3ones(2)
diff --git a/test/runtests.jl b/test/runtests.jl
index 363d9fb..13550e2 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -58,4 +58,7 @@ if GROUP == "All" || GROUP == "Downstream"
     @safetestset "remake_buffer with array symbolics test" begin
         @time include("downstream/remake_arrayvars.jl")
     end
+    @safetestset "array indexing" begin
+        @time include("downstream/array_indexing.jl")
+    end
 end