diff --git a/src/systems/problem_utils.jl b/src/systems/problem_utils.jl
index e099ffafbe..b893d9ffc6 100644
--- a/src/systems/problem_utils.jl
+++ b/src/systems/problem_utils.jl
@@ -659,7 +659,8 @@ end
     $(TYPEDEF)
 
 A callable struct which applies `p_constructor` to possibly nested arrays. It also
-ensures that views (including nested ones) are concretized.
+ensures that views (including nested ones) are concretized. This is implemented manually
+of using `narrow_buffer_type` to preserve type-stability.
 """
 struct PConstructorApplicator{F}
     p_constructor::F
@@ -669,10 +670,18 @@ function (pca::PConstructorApplicator)(x::AbstractArray)
     pca.p_constructor(x)
 end
 
+function (pca::PConstructorApplicator)(x::AbstractArray{Bool})
+    pca.p_constructor(BitArray(x))
+end
+
 function (pca::PConstructorApplicator{typeof(identity)})(x::SubArray)
     collect(x)
 end
 
+function (pca::PConstructorApplicator{typeof(identity)})(x::SubArray{Bool})
+    BitArray(x)
+end
+
 function (pca::PConstructorApplicator{typeof(identity)})(x::SubArray{<:AbstractArray})
     collect(pca.(x))
 end
@@ -695,6 +704,7 @@ takes a value provider of `srcsys` and a value provider of `dstsys` and returns
 """
 function get_mtkparameters_reconstructor(srcsys::AbstractSystem, dstsys::AbstractSystem;
         initials = false, unwrap_initials = false, p_constructor = identity)
+    _p_constructor = p_constructor
     p_constructor = PConstructorApplicator(p_constructor)
     # if we call `getu` on this (and it were able to handle empty tuples) we get the
     # fields of `MTKParameters` except caches.
@@ -748,14 +758,24 @@ function get_mtkparameters_reconstructor(srcsys::AbstractSystem, dstsys::Abstrac
         Base.Fix1(broadcast, p_constructor) ∘
         getu(srcsys, syms[3])
     end
-    rest_getters = map(Base.tail(Base.tail(Base.tail(syms)))) do buf
-        if buf == ()
-            return Returns(())
-        else
-            return Base.Fix1(broadcast, p_constructor) ∘ getu(srcsys, buf)
-        end
+    const_getter = if syms[4] == ()
+        Returns(())
+    else
+        Base.Fix1(broadcast, p_constructor) ∘ getu(srcsys, syms[4])
     end
-    getters = (tunable_getter, initials_getter, discs_getter, rest_getters...)
+    nonnumeric_getter = if syms[5] == ()
+        Returns(())
+    else
+        ic = get_index_cache(dstsys)
+        buftypes = Tuple(map(ic.nonnumeric_buffer_sizes) do bufsize
+            Vector{bufsize.type}
+        end)
+        # nonnumerics retain the assigned buffer type without narrowing
+        Base.Fix1(broadcast, _p_constructor) ∘
+        Base.Fix1(Broadcast.BroadcastFunction(call), buftypes) ∘ getu(srcsys, syms[5])
+    end
+    getters = (
+        tunable_getter, initials_getter, discs_getter, const_getter, nonnumeric_getter)
     getter = let getters = getters
         function _getter(valp, initprob)
             oldcache = parameter_values(initprob).caches
@@ -768,6 +788,10 @@ function get_mtkparameters_reconstructor(srcsys::AbstractSystem, dstsys::Abstrac
     return getter
 end
 
+function call(f, args...)
+    f(args...)
+end
+
 """
     $(TYPEDSIGNATURES)
 
diff --git a/test/code_generation.jl b/test/code_generation.jl
index 05b945f503..b48e4acf64 100644
--- a/test/code_generation.jl
+++ b/test/code_generation.jl
@@ -89,7 +89,7 @@ end
     end
     @mtkbuild sys = ODESystem([D(x) ~ y[1] + y[2], y ~ foo(x)], t)
     @test length(equations(sys)) == 1
-    @test length(observed(sys)) == 3
+    @test length(ModelingToolkit.observed(sys)) == 3
     prob = ODEProblem(sys, [x => 1.0], (0.0, 1.0), [foo => _tmp_fn2])
     val[] = 0
     @test_nowarn prob.f(prob.u0, prob.p, 0.0)
@@ -101,7 +101,7 @@ end
         @mtkbuild sys = ODESystem(
             [D(y) ~ foo(x), D(x) ~ sum(y), zeros(2) ~ foo(prod(z))], t)
         @test length(equations(sys)) == 5
-        @test length(observed(sys)) == 0
+        @test length(ModelingToolkit.observed(sys)) == 0
         prob = ODEProblem(
             sys, [y => ones(2), z => 2ones(2), x => 3.0], (0.0, 1.0), [foo => _tmp_fn2])
         val[] = 0
diff --git a/test/initializationsystem.jl b/test/initializationsystem.jl
index b1ba21b254..fd84c346f9 100644
--- a/test/initializationsystem.jl
+++ b/test/initializationsystem.jl
@@ -1671,3 +1671,23 @@ end
     sol = solve(prob, Tsit5())
     @test SciMLBase.successful_retcode(sol)
 end
+
+@testset "Nonnumerics aren't narrowed" begin
+    @mtkmodel Foo begin
+        @variables begin
+            x(t) = 1.0
+        end
+        @parameters begin
+            p::AbstractString
+            r = 1.0
+        end
+        @equations begin
+            D(x) ~ r * x
+        end
+    end
+    @mtkbuild sys = Foo(p = "a")
+    prob = ODEProblem(sys, [], (0.0, 1.0))
+    @test prob.p.nonnumeric[1] isa Vector{AbstractString}
+    integ = init(prob)
+    @test integ.p.nonnumeric[1] isa Vector{AbstractString}
+end