diff --git a/src/MLJInterface.jl b/src/MLJInterface.jl
index 3a8d0a1d..1cc34fe4 100644
--- a/src/MLJInterface.jl
+++ b/src/MLJInterface.jl
@@ -32,6 +32,7 @@ using ..ComplexityModule: compute_complexity
 using ..HallOfFameModule: HallOfFame, format_hall_of_fame
 using ..UtilsModule: subscriptify, @ignore
 using ..LoggingModule: AbstractSRLogger
+using ..TemplateExpressionModule: TemplateExpression
 
 import ..equation_search
 
@@ -50,8 +51,9 @@ end
 
 """Generate an `SRRegressor` struct containing all the fields in `Options`."""
 function modelexpr(model_name::Symbol)
-    struct_def = :(Base.@kwdef mutable struct $(model_name){D<:AbstractDimensions,L} <:
-                                 AbstractSRRegressor
+    struct_def = :(Base.@kwdef mutable struct $(model_name){
+        D<:AbstractDimensions,L,E<:AbstractExpression
+    } <: AbstractSRRegressor
         niterations::Int = 100
         parallelism::Symbol = :multithreading
         numprocs::Union{Int,Nothing} = nothing
@@ -62,7 +64,7 @@ function modelexpr(model_name::Symbol)
         logger::Union{AbstractSRLogger,Nothing} = nothing
         runtests::Bool = true
         run_id::Union{String,Nothing} = nothing
-        loss_type::L = Nothing
+        loss_type::Type{L} = Nothing
         selection_method::Function = choose_best
         dimensions_type::Type{D} = SymbolicDimensions{DEFAULT_DIM_BASE_TYPE}
     end)
@@ -71,7 +73,14 @@ function modelexpr(model_name::Symbol)
 
     # Add everything from `Options` constructor directly to struct:
     for (i, option) in enumerate(DEFAULT_OPTIONS)
+        if getsymb(first(option.args)) == :expression_type
+            continue
+        end
         insert!(fields, i, Expr(:(=), option.args...))
+        if getsymb(first(option.args)) == :node_type
+            # Manually add `expression_type` above, so it can be depended on by `node_type`
+            insert!(fields, i - 1, :(expression_type::Type{E} = Expression))
+        end
     end
 
     # We also need to create the `get_options` function, based on this:
@@ -597,7 +606,7 @@ const input_scitype = Union{
 MMI.metadata_model(
     SRRegressor;
     input_scitype,
-    target_scitype=AbstractVector{<:Any},
+    target_scitype=AbstractVector{<:MMI.Continuous},
     supports_weights=true,
     reports_feature_importances=false,
     load_path="SymbolicRegression.MLJInterfaceModule.SRRegressor",
@@ -606,13 +615,22 @@ MMI.metadata_model(
 MMI.metadata_model(
     MultitargetSRRegressor;
     input_scitype,
-    target_scitype=Union{MMI.Table(Any),AbstractMatrix{<:Any}},
+    target_scitype=Union{MMI.Table(MMI.Continuous),AbstractMatrix{<:MMI.Continuous}},
     supports_weights=true,
     reports_feature_importances=false,
     load_path="SymbolicRegression.MLJInterfaceModule.MultitargetSRRegressor",
     human_name="Multi-Target Symbolic Regression via Evolutionary Search",
 )
 
+function MMI.target_scitype(::Type{<:SRRegressor{<:Any,<:Any,<:TemplateExpression}})
+    return AbstractVector{<:Any}
+end
+function MMI.target_scitype(
+    ::Type{<:MultitargetSRRegressor{<:Any,<:Any,<:TemplateExpression}}
+)
+    return Union{MMI.Table(Any),AbstractMatrix{<:Any}}
+end
+
 function tag_with_docstring(model_name::Symbol, description::String, bottom_matter::String)
     docstring = """$(MMI.doc_header(eval(model_name)))