diff --git a/src/SyntacticModels.jl b/src/SyntacticModels.jl
index 7b8f02f..12d9290 100644
--- a/src/SyntacticModels.jl
+++ b/src/SyntacticModels.jl
@@ -51,7 +51,9 @@ include("composite_models.jl")
 #-----------------------------------------------------------------------------# Constructors
 for T in concrete_subtypes(AbstractTerm)
     @eval function $(parentmodule(T)).$(T.name.name)(x::NamedTuple)
-        args = x[fieldnames($T)]
+        fields = filter(x -> x != :_type, fieldnames($T))
+        args = collect(x[fields])
+        @show args
         $(parentmodule(T)).$(T.name.name)(args...)
     end
 end
diff --git a/test/core.jl b/test/core.jl
index 55f9996..600eaf5 100644
--- a/test/core.jl
+++ b/test/core.jl
@@ -9,7 +9,7 @@ using JSON3
 jsondir = joinpath(@__DIR__, "json")
 
 write_json_model(m, prefix=joinpath(@__DIR__, "json")) = open(joinpath(prefix, "$(m.header.name).json"), "w") do fp
-  JSON3.pretty(fp, Dict(m))
+  JSON3.pretty(fp, m)
 end
 
 readback(m, prefix=joinpath(@__DIR__, "json")) = open(joinpath(jsondir, "$(m.header.name).json"), "r") do fp