diff --git a/src/Configuration.jl b/src/Configuration.jl
index 5cc95b0ada..b99c429723 100644
--- a/src/Configuration.jl
+++ b/src/Configuration.jl
@@ -167,16 +167,6 @@ These options are not intended to be changed during normal use.
     workspace_custom_startup_expr::Union{Nothing,String} = WORKSPACE_CUSTOM_STARTUP_EXPR_DEFAULT
 end
 
-# TODO: deprecated, remove me in the next breaking release
-function Base.setproperty!(x::EvaluationOptions, property::Symbol, val)
-    if property === :workspace_custom_startup_expr && val isa Expr
-        @warn "Deprecated: workspace_custom_startup_expr should be a String, not an Expr."
-        setfield!(x, property, string(val))            
-    else
-        setfield!(x, property, val)
-    end
-end
-
 const COMPILE_DEFAULT = nothing
 const PKGIMAGES_DEFAULT = nothing
 const COMPILED_MODULES_DEFAULT = nothing
diff --git a/test/Configuration.jl b/test/Configuration.jl
index 227e3d277e..8b92d5b179 100644
--- a/test/Configuration.jl
+++ b/test/Configuration.jl
@@ -128,16 +128,8 @@ end
 @testset "disable mimetype via workspace_custom_startup_expr" begin
     🍭 = ServerSession()
     🍭.options.evaluation.workspace_use_distributed = true
-    🍭.options.evaluation.workspace_custom_startup_expr = quote
-        PlutoRunner.is_mime_enabled(m::MIME"application/vnd.pluto.tree+object") = false
-    end
-
-    # backwards compat: setting the value to an Expr should still work
-    @test 🍭.options.evaluation.workspace_custom_startup_expr isa String
-    @test occursin("PlutoRunner.is_mime_enabled", 🍭.options.evaluation.workspace_custom_startup_expr)
-
-    # normally you set it to a String
     🍭.options.evaluation.workspace_custom_startup_expr = """
+        1 + 1
         PlutoRunner.is_mime_enabled(m::MIME"application/vnd.pluto.tree+object") = false
     """