diff --git a/src/macros.jl b/src/macros.jl
index a8dab61..3cfd974 100644
--- a/src/macros.jl
+++ b/src/macros.jl
@@ -74,18 +74,47 @@ macro test_trixi_include_base(elixir, args...)
     local atol = get_kwarg(args, :atol, atol_default)
     local rtol = get_kwarg(args, :rtol, rtol_default)
 
-    local kwargs = Pair{Symbol, Any}[]
+    # Build escaped kwarg expressions. For bare-symbol values there are three cases:
+    #   1. Symbol is also a key in this kwarg list (e.g. `seed=6, x=seed`): always pass
+    #      as Symbol so trixi_include resolves it inside the elixir after the other
+    #      override (seed=6) has been applied.
+    #   2. Locally-defined values defined in the testset body:
+    #      @isdefined returns true (same world age), so the actual value is passed.
+    #   3. Elixir-internal variable references (e.g. bare `x=seed` with no seed= key):
+    #      on Julia >= 1.12, @isdefined returns false because bindings set inside
+    #      Base.include have a newer world age; on older Julia the value is visible and
+    #      also correct (same as the elixir default).
+    # For non-Symbol expressions (closures, calls, literals), always evaluate at call site.
+    local kwarg_keys = Set(arg.args[1]
+                           for arg in args
+                           if arg.head == :(=) &&
+                              !(arg.args[1] in (:additional_ignore_content, :l2, :linf,
+                                                :RealT_for_test_tolerances, :atol, :rtol)))
+    local kwarg_exprs = Expr[]
     for arg in args
         if (arg.head == :(=) &&
             !(arg.args[1] in (:additional_ignore_content, :l2, :linf,
                               :RealT_for_test_tolerances, :atol, :rtol)))
-            push!(kwargs, Pair(arg.args...))
+            key = arg.args[1]
+            val = arg.args[2]
+            if val isa Symbol && val in kwarg_keys
+                # Case 1: chained override — pass as Symbol for elixir-internal resolution
+                push!(kwarg_exprs, Expr(:kw, key, QuoteNode(val)))
+            elseif val isa Symbol
+                # Cases 2 & 3: use @isdefined to capture locally-defined values while
+                # falling back to Symbol for elixir-internal references
+                push!(kwarg_exprs,
+                      Expr(:kw, key,
+                           esc(:((@isdefined $val) ? $val : $(QuoteNode(val))))))
+            else
+                push!(kwarg_exprs, Expr(:kw, key, esc(val)))
+            end
         end
     end
 
     # if `maxiters` is set in tests, it is usually set to a small number to
     # run only a few steps - ignore possible warnings coming from that
-    if any(==(:maxiters) ∘ first, kwargs)
+    if any(e -> e.args[1] == :maxiters, kwarg_exprs)
         args = append_to_kwargs(args, :additional_ignore_content,
                                 [
                                     r"┌ Warning: Verbosity toggle: max_iters \n│  Interrupted\. Larger maxiters is needed\..*\n└ @ SciMLBase .+\n",
@@ -99,7 +128,7 @@ macro test_trixi_include_base(elixir, args...)
         mpi_isroot() && println($(esc(elixir)))
 
         # evaluate examples in the scope of the module they're called from
-        @trixi_test_nowarn trixi_include(@__MODULE__, $(esc(elixir)); $kwargs...) $additional_ignore_content
+        @trixi_test_nowarn trixi_include(@__MODULE__, $(esc(elixir)); $(kwarg_exprs...)) $additional_ignore_content
 
         # if present, compare l2 and linf errors against reference values
         if !isnothing($l2) || !isnothing($linf)
diff --git a/test/test_test_trixi_include.jl b/test/test_test_trixi_include.jl
index bc3e22a..a8ebe5d 100644
--- a/test/test_test_trixi_include.jl
+++ b/test/test_test_trixi_include.jl
@@ -20,45 +20,25 @@ end
 
             # just include
             @test_trixi_include_base(path)
-            if VERSION >= v"1.12"
-                mod = @__MODULE__
-                @test @invokelatest isdefined(mod, :x)
-                @test (@invokelatest mod.x) == 4
-            else
-                @test @isdefined x
-                @test x == 4
-            end
+            mod = @__MODULE__
+            @test @invokelatest isdefined(mod, :x)
+            @test (@invokelatest mod.x) == 4
 
             @test_trixi_include(path)
-            if VERSION >= v"1.12"
-                mod = @__MODULE__
-                @test @invokelatest isdefined(mod, :x)
-                @test (@invokelatest mod.x) == 4
-            else
-                @test @isdefined x
-                @test x == 4
-            end
+            mod = @__MODULE__
+            @test @invokelatest isdefined(mod, :x)
+            @test (@invokelatest mod.x) == 4
 
             # include and overwrite included variable by a constant
             @test_trixi_include_base(path, x=9)
-            if VERSION >= v"1.12"
-                mod = @__MODULE__
-                @test @invokelatest isdefined(mod, :x)
-                @test (@invokelatest mod.x) == 9
-            else
-                @test @isdefined x
-                @test x == 9
-            end
+            mod = @__MODULE__
+            @test @invokelatest isdefined(mod, :x)
+            @test (@invokelatest mod.x) == 9
 
             @test_trixi_include(path, x=9)
-            if VERSION >= v"1.12"
-                mod = @__MODULE__
-                @test @invokelatest isdefined(mod, :x)
-                @test (@invokelatest mod.x) == 9
-            else
-                @test @isdefined x
-                @test x == 9
-            end
+            mod = @__MODULE__
+            @test @invokelatest isdefined(mod, :x)
+            @test (@invokelatest mod.x) == 9
         end
     end
 
@@ -75,66 +55,159 @@ end
             # overwrite included variable by a (global) variable
             global override = 5
             @test_trixi_include_base(path, x=override)
-            if VERSION >= v"1.12"
-                mod = @__MODULE__
-                @test @invokelatest isdefined(mod, :x)
-                @test (@invokelatest mod.x) == 5
-            else
-                @test @isdefined x
-                @test x == 5
-            end
+            mod = @__MODULE__
+            @test @invokelatest isdefined(mod, :x)
+            @test (@invokelatest mod.x) == 5
 
             @test_trixi_include(path, x=override)
-            if VERSION >= v"1.12"
-                mod = @__MODULE__
-                @test @invokelatest isdefined(mod, :x)
-                @test (@invokelatest mod.x) == 5
-            else
-                @test @isdefined x
-                @test x == 5
-            end
+            mod = @__MODULE__
+            @test @invokelatest isdefined(mod, :x)
+            @test (@invokelatest mod.x) == 5
 
             # overwrite included variable by another included variable
             @test_trixi_include_base(path, x=seed)
-            if VERSION >= v"1.12"
-                mod = @__MODULE__
-                @test @invokelatest isdefined(mod, :x)
-                @test (@invokelatest mod.x) == 42
-            else
-                @test @isdefined x
-                @test x == 42
-            end
+            mod = @__MODULE__
+            @test @invokelatest isdefined(mod, :x)
+            @test (@invokelatest mod.x) == 42
 
             @test_trixi_include(path, x=seed)
-            if VERSION >= v"1.12"
-                mod = @__MODULE__
-                @test @invokelatest isdefined(mod, :x)
-                @test (@invokelatest mod.x) == 42
-            else
-                @test @isdefined x
-                @test x == 42
-            end
+            mod = @__MODULE__
+            @test @invokelatest isdefined(mod, :x)
+            @test (@invokelatest mod.x) == 42
 
             # overwrite included variable by supplied variable
             @test_trixi_include_base(path, seed=6, x=seed)
-            if VERSION >= v"1.12"
-                mod = @__MODULE__
-                @test @invokelatest isdefined(mod, :x)
-                @test (@invokelatest mod.x) == 6
-            else
-                @test @isdefined x
-                @test x == 6
-            end
+            mod = @__MODULE__
+            @test @invokelatest isdefined(mod, :x)
+            @test (@invokelatest mod.x) == 6
 
             @test_trixi_include(path, seed=6, x=seed)
-            if VERSION >= v"1.12"
-                mod = @__MODULE__
-                @test @invokelatest isdefined(mod, :x)
-                @test (@invokelatest mod.x) == 6
-            else
-                @test @isdefined x
-                @test x == 6
+            mod = @__MODULE__
+            @test @invokelatest isdefined(mod, :x)
+            @test (@invokelatest mod.x) == 6
+        end
+    end
+
+    @trixi_testset "normal override, all assignment forms" begin
+        global f(; x = 0) = x
+        example = """
+            x = 1
+            x_kw_pos  = f(x = 1)
+            x_kw_semi = f(; x = 1)
+            y = (; x = 1)
+            function g(; x = 1)
+                return x
             end
+            y_g = g()
+            function h(x = 1)
+                return x
+            end
+            y_h = h()
+            y_let = 0
+            y_let_global = 0
+            let x = 1
+                y_let = x
+                global y_let_global = x
+            end
+            """
+
+        mktemp() do path, io
+            write(io, example)
+            close(io)
+
+            @test_trixi_include_base(path, x=6)
+            mod = @__MODULE__
+            @test (@invokelatest mod.x) == 6
+            @test (@invokelatest mod.x_kw_pos) == 6
+            @test (@invokelatest mod.x_kw_semi) == 6
+            @test (@invokelatest mod.y).x == 6
+            @test (@invokelatest mod.y_g) == 6
+            @test (@invokelatest mod.y_h) == 6
+            @test (@invokelatest mod.y_let) == 0 # let block introduces a local scope
+            @test (@invokelatest mod.y_let_global) == 6
+        end
+    end
+
+    @trixi_testset "chained override, all assignment forms" begin
+        global f(; x = 0) = x
+        example = """
+            seed = 42
+            x = 1
+            x_kw_pos  = f(x = 1)
+            x_kw_semi = f(; x = 1)
+            y = (; x = 1)
+            function g(; x = 1)
+                return x
+            end
+            y_g = g()
+            function h(x = 1)
+                return x
+            end
+            y_h = h()
+            y_let = 0
+            y_let_global = 0
+            let x = 1
+                y_let = x
+                global y_let_global = x
+            end
+            """
+
+        mktemp() do path, io
+            write(io, example)
+            close(io)
+
+            @test_trixi_include_base(path, seed=6, x=seed)
+            mod = @__MODULE__
+            @test (@invokelatest mod.x) == 6
+            @test (@invokelatest mod.x_kw_pos) == 6
+            @test (@invokelatest mod.x_kw_semi) == 6
+            @test (@invokelatest mod.y).x == 6
+            @test (@invokelatest mod.y_g) == 6
+            @test (@invokelatest mod.y_h) == 6
+            @test (@invokelatest mod.y_let) == 0 # let block introduces a local scope
+            @test (@invokelatest mod.y_let_global) == 6
+        end
+    end
+
+    @trixi_testset "locally defined override, all assignment forms" begin
+        global f(; x = 0) = x
+        example = """
+            x = 1
+            x_kw_pos  = f(x = 1)
+            x_kw_semi = f(; x = 1)
+            y = (; x = 1)
+            function g(; x = 1)
+                return x
+            end
+            y_g = g()
+            function h(x = 1)
+                return x
+            end
+            y_h = h()
+            y_let = 0
+            y_let_global = 0
+            let x = 1
+                y_let = x
+                global y_let_global = x
+            end
+            """
+
+        mktemp() do path, io
+            write(io, example)
+            close(io)
+
+            # overwrite included variable by a locally defined value (not a module global)
+            local_x = 6
+            @test_trixi_include_base(path, x=local_x)
+            mod = @__MODULE__
+            @test (@invokelatest mod.x) == 6
+            @test (@invokelatest mod.x_kw_pos) == 6
+            @test (@invokelatest mod.x_kw_semi) == 6
+            @test (@invokelatest mod.y).x == 6
+            @test (@invokelatest mod.y_g) == 6
+            @test (@invokelatest mod.y_h) == 6
+            @test (@invokelatest mod.y_let) == 0 # let block introduces a local scope
+            @test (@invokelatest mod.y_let_global) == 6
         end
     end
 
@@ -236,24 +309,14 @@ end
             close(io)
 
             @test_trixi_include_base(path, RealT=Float32)
-            if VERSION >= v"1.12"
-                mod = @__MODULE__
-                @test @invokelatest isdefined(mod, :RealT)
-                @test (@invokelatest mod.RealT) == Float32
-            else
-                @test @isdefined RealT
-                @test RealT == Float32
-            end
+            mod = @__MODULE__
+            @test @invokelatest isdefined(mod, :RealT)
+            @test (@invokelatest mod.RealT) == Float32
 
             @test_trixi_include(path, RealT=Float32)
-            if VERSION >= v"1.12"
-                mod = @__MODULE__
-                @test @invokelatest isdefined(mod, :RealT)
-                @test (@invokelatest mod.RealT) == Float32
-            else
-                @test @isdefined RealT
-                @test RealT == Float32
-            end
+            mod = @__MODULE__
+            @test @invokelatest isdefined(mod, :RealT)
+            @test (@invokelatest mod.RealT) == Float32
         end
     end
 end