diff --git a/src/systems/model_parsing.jl b/src/systems/model_parsing.jl
index b10b7125a2..5df951a566 100644
--- a/src/systems/model_parsing.jl
+++ b/src/systems/model_parsing.jl
@@ -51,7 +51,7 @@ function _model_macro(mod, name, expr, isconnector)
     c_evts = []
     d_evts = []
     kwargs = OrderedCollections.OrderedSet()
-    where_types = Expr[]
+    where_types = Union{Symbol, Expr}[]
 
     push!(exprs.args, :(variables = []))
     push!(exprs.args, :(parameters = []))
@@ -143,9 +143,15 @@ end
 pop_structure_dict!(dict, key) = length(dict[key]) == 0 && pop!(dict, key)
 
 function update_kwargs_and_metadata!(dict, kwargs, a, def, indices, type, var,
-        varclass, where_types)
+        varclass, where_types, meta)
     if indices isa Nothing
-        push!(kwargs, Expr(:kw, Expr(:(::), a, Union{Nothing, type}), nothing))
+        if !isnothing(meta) && haskey(meta, VariableUnit)
+            uvar = gensym()
+            push!(where_types, uvar)
+            push!(kwargs, Expr(:kw, :($a::Union{Nothing, $uvar}), nothing))
+        else
+            push!(kwargs, Expr(:kw, :($a::Union{Nothing, $type}), nothing))
+        end
         dict[:kwargs][getname(var)] = Dict(:value => def, :type => type)
     else
         vartype = gensym(:T)
@@ -154,7 +160,11 @@ function update_kwargs_and_metadata!(dict, kwargs, a, def, indices, type, var,
                 Expr(:(::), a,
                     Expr(:curly, :Union, :Nothing, Expr(:curly, :AbstractArray, vartype))),
                 nothing))
-        push!(where_types, :($vartype <: $type))
+        if !isnothing(meta) && haskey(meta, VariableUnit)
+            push!(where_types, vartype)
+        else
+            push!(where_types, :($vartype <: $type))
+        end
         dict[:kwargs][getname(var)] = Dict(:value => def, :type => AbstractArray{type})
     end
     if dict[varclass] isa Vector
@@ -166,7 +176,7 @@ end
 
 function parse_variable_def!(dict, mod, arg, varclass, kwargs, where_types;
         def = nothing, indices::Union{Vector{UnitRange{Int}}, Nothing} = nothing,
-        type::Type = Real)
+        type::Type = Real, meta = Dict{DataType, Expr}())
     metatypes = [(:connection_type, VariableConnectType),
         (:description, VariableDescription),
         (:unit, VariableUnit),
@@ -186,29 +196,31 @@ function parse_variable_def!(dict, mod, arg, varclass, kwargs, where_types;
         a::Symbol => begin
             var = generate_var!(dict, a, varclass; indices, type)
             update_kwargs_and_metadata!(dict, kwargs, a, def, indices, type, var,
-                varclass, where_types)
+                varclass, where_types, meta)
             return var, def, Dict()
         end
         Expr(:(::), a, type) => begin
             type = getfield(mod, type)
-            parse_variable_def!(dict, mod, a, varclass, kwargs, where_types; def, type)
+            parse_variable_def!(
+                dict, mod, a, varclass, kwargs, where_types; def, type, meta)
         end
         Expr(:(::), Expr(:call, a, b), type) => begin
             type = getfield(mod, type)
             def = _type_check!(def, a, type, varclass)
-            parse_variable_def!(dict, mod, a, varclass, kwargs, where_types; def, type)
+            parse_variable_def!(
+                dict, mod, a, varclass, kwargs, where_types; def, type, meta)
         end
         Expr(:call, a, b) => begin
             var = generate_var!(dict, a, b, varclass, mod; indices, type)
             update_kwargs_and_metadata!(dict, kwargs, a, def, indices, type, var,
-                varclass, where_types)
+                varclass, where_types, meta)
             return var, def, Dict()
         end
         Expr(:(=), a, b) => begin
             Base.remove_linenums!(b)
             def, meta = parse_default(mod, b)
             var, def, _ = parse_variable_def!(
-                dict, mod, a, varclass, kwargs, where_types; def, type)
+                dict, mod, a, varclass, kwargs, where_types; def, type, meta)
             if dict[varclass] isa Vector
                 dict[varclass][1][getname(var)][:default] = def
             else
@@ -231,9 +243,9 @@ function parse_variable_def!(dict, mod, arg, varclass, kwargs, where_types;
             return var, def, Dict()
         end
         Expr(:tuple, a, b) => begin
-            var, def, _ = parse_variable_def!(
-                dict, mod, a, varclass, kwargs, where_types; type)
             meta = parse_metadata(mod, b)
+            var, def, _ = parse_variable_def!(
+                dict, mod, a, varclass, kwargs, where_types; type, meta)
             if meta !== nothing
                 for (type, key) in metatypes
                     if (mt = get(meta, key, nothing)) !== nothing
@@ -253,7 +265,7 @@ function parse_variable_def!(dict, mod, arg, varclass, kwargs, where_types;
         Expr(:ref, a, b...) => begin
             indices = map(i -> UnitRange(i.args[2], i.args[end]), b)
             parse_variable_def!(dict, mod, a, varclass, kwargs, where_types;
-                def, indices, type)
+                def, indices, type, meta)
         end
         _ => error("$arg cannot be parsed")
     end
@@ -611,16 +623,58 @@ function parse_variable_arg!(exprs, vs, dict, mod, arg, varclass, kwargs, where_
     push!(exprs, ex)
 end
 
+function convert_units(varunits::DynamicQuantities.Quantity, value)
+    DynamicQuantities.ustrip(DynamicQuantities.uconvert(
+        DynamicQuantities.SymbolicUnits.as_quantity(varunits), value))
+end
+
+function convert_units(
+        varunits::DynamicQuantities.Quantity, value::AbstractArray{T}) where {T}
+    DynamicQuantities.ustrip.(DynamicQuantities.uconvert.(
+        DynamicQuantities.SymbolicUnits.as_quantity(varunits), value))
+end
+
+function convert_units(varunits::Unitful.FreeUnits, value)
+    Unitful.ustrip(varunits, value)
+end
+
+function convert_units(varunits::Unitful.FreeUnits, value::AbstractArray{T}) where {T}
+    Unitful.ustrip.(varunits, value)
+end
+
 function parse_variable_arg(dict, mod, arg, varclass, kwargs, where_types)
     vv, def, metadata_with_exprs = parse_variable_def!(
         dict, mod, arg, varclass, kwargs, where_types)
     name = getname(vv)
 
-    varexpr = quote
-        $name = if $name === nothing
-            $setdefault($vv, $def)
-        else
-            $setdefault($vv, $name)
+    varexpr = if haskey(metadata_with_exprs, VariableUnit)
+        unit = metadata_with_exprs[VariableUnit]
+        quote
+            $name = if $name === nothing
+                $setdefault($vv, $def)
+            else
+                try
+                    $setdefault($vv, $convert_units($unit, $name))
+                catch e
+                    if isa(e, $(DynamicQuantities.DimensionError)) ||
+                       isa(e, $(Unitful.DimensionError))
+                        error("Unable to convert units for \'" * string(:($$vv)) * "\'")
+                    elseif isa(e, MethodError)
+                        error("No or invalid units provided for \'" * string(:($$vv)) *
+                              "\'")
+                    else
+                        rethrow(e)
+                    end
+                end
+            end
+        end
+    else
+        quote
+            $name = if $name === nothing
+                $setdefault($vv, $def)
+            else
+                $setdefault($vv, $name)
+            end
         end
     end
 
diff --git a/test/dq_units.jl b/test/dq_units.jl
index 75bbd4c4a9..76a9c5aa11 100644
--- a/test/dq_units.jl
+++ b/test/dq_units.jl
@@ -157,3 +157,31 @@ maj2 = MassActionJump(γ, [I => 1], [I => -1, R => 1])
 maj1 = MassActionJump(2.0, [0 => 1], [S => 1])
 maj2 = MassActionJump(γ, [S => 1], [S => -1])
 @named js4 = JumpSystem([maj1, maj2], ModelingToolkit.t_nounits, [S], [β, γ])
+
+@mtkmodel ParamTest begin
+    @parameters begin
+        a, [unit = u"m"]
+    end
+    @variables begin
+        b(t), [unit = u"kg"]
+    end
+end
+
+@named sys = ParamTest()
+
+@named sys = ParamTest(a = 3.0u"cm")
+@test ModelingToolkit.getdefault(sys.a) ≈ 0.03
+
+@test_throws ErrorException ParamTest(; name = :t, a = 1.0)
+@test_throws ErrorException ParamTest(; name = :t, a = 1.0u"s")
+
+@mtkmodel ArrayParamTest begin
+    @parameters begin
+        a[1:2], [unit = u"m"]
+    end
+end
+
+@named sys = ArrayParamTest()
+
+@named sys = ArrayParamTest(a = [1.0, 3.0]u"cm")
+@test ModelingToolkit.getdefault(sys.a) ≈ [0.01, 0.03]
diff --git a/test/model_parsing.jl b/test/model_parsing.jl
index 9236dfc975..352c2ee3d4 100644
--- a/test/model_parsing.jl
+++ b/test/model_parsing.jl
@@ -1,7 +1,8 @@
 using ModelingToolkit, Test
 using ModelingToolkit: get_connector_type, get_defaults, get_gui_metadata,
                        get_systems, get_ps, getdefault, getname, readable_code,
-                       scalarize, symtype, VariableDescription, RegularConnector
+                       scalarize, symtype, VariableDescription, RegularConnector,
+                       get_unit
 using URIs: URI
 using Distributions
 using DynamicQuantities, OrdinaryDiffEq
@@ -53,8 +54,9 @@ end
     end
 end
 
-@named p = Pin(; v = π)
-@test getdefault(p.v) == π
+@named p = Pin(; v = π * u"V")
+
+@test getdefault(p.v) ≈ π
 @test Pin.isconnector == true
 
 @mtkmodel OnePort begin
@@ -76,7 +78,6 @@ end
 
 @test OnePort.isconnector == false
 
-resistor_log = "$(@__DIR__)/logo/resistor.svg"
 @mtkmodel Resistor begin
     @extend v, i = oneport = OnePort()
     @parameters begin
@@ -105,14 +106,14 @@ end
     @parameters begin
         C, [unit = u"F"]
     end
-    @extend OnePort(; v = 0.0)
+    @extend OnePort(; v = 0.0u"V")
     @icon "https://upload.wikimedia.org/wikipedia/commons/7/78/Capacitor_symbol.svg"
     @equations begin
         D(v) ~ i / C
     end
 end
 
-@named capacitor = Capacitor(C = 10, v = 10.0)
+@named capacitor = Capacitor(C = 10u"F", v = 10.0u"V")
 @test getdefault(capacitor.v) == 10.0
 
 @mtkmodel Voltage begin
@@ -127,9 +128,9 @@ end
 
 @mtkmodel RC begin
     @structural_parameters begin
-        R_val = 10
-        C_val = 10
-        k_val = 10
+        R_val = 10u"Ω"
+        C_val = 10u"F"
+        k_val = 10u"V"
     end
     @components begin
         resistor = Resistor(; R = R_val)
@@ -147,9 +148,9 @@ end
     end
 end
 
-C_val = 20
-R_val = 20
-res__R = 100
+C_val = 20u"F"
+R_val = 20u"Ω"
+res__R = 100u"Ω"
 @mtkbuild rc = RC(; C_val, R_val, resistor.R = res__R)
 prob = ODEProblem(rc, [], (0, 1e9))
 sol = solve(prob, Rodas5P())
@@ -160,11 +161,12 @@ resistor = getproperty(rc, :resistor; namespace = false)
 @test getname(rc.resistor.R) === getname(resistor.R)
 @test getname(rc.resistor.v) === getname(resistor.v)
 # Test that `resistor.R` overrides `R_val` in the argument.
-@test getdefault(rc.resistor.R) == res__R != R_val
+@test getdefault(rc.resistor.R) * get_unit(rc.resistor.R) == res__R != R_val
 # Test that `C_val` passed via argument is set as default of C.
-@test getdefault(rc.capacitor.C) == C_val
+@test getdefault(rc.capacitor.C) * get_unit(rc.capacitor.C) == C_val
 # Test that `k`'s default value is unchanged.
-@test getdefault(rc.constant.k) == RC.structure[:kwargs][:k_val][:value]
+@test getdefault(rc.constant.k) * get_unit(rc.constant.k) ==
+      eval(RC.structure[:kwargs][:k_val][:value])
 @test getdefault(rc.capacitor.v) == 0.0
 
 @test get_gui_metadata(rc.resistor).layout == Resistor.structure[:icon] ==
diff --git a/test/units.jl b/test/units.jl
index 033a64c0e3..8d7f9e451e 100644
--- a/test/units.jl
+++ b/test/units.jl
@@ -192,3 +192,31 @@ maj2 = MassActionJump(γ, [I => 1], [I => -1, R => 1])
 maj1 = MassActionJump(2.0, [0 => 1], [S => 1])
 maj2 = MassActionJump(γ, [S => 1], [S => -1])
 @named js4 = JumpSystem([maj1, maj2], t, [S], [β, γ])
+
+@mtkmodel ParamTest begin
+    @parameters begin
+        a, [unit = u"m"]
+    end
+    @variables begin
+        b(t), [unit = u"kg"]
+    end
+end
+
+@named sys = ParamTest()
+
+@named sys = ParamTest(a = 3.0u"cm")
+@test ModelingToolkit.getdefault(sys.a) ≈ 0.03
+
+@test_throws ErrorException ParamTest(; name = :t, a = 1.0)
+@test_throws ErrorException ParamTest(; name = :t, a = 1.0u"s")
+
+@mtkmodel ArrayParamTest begin
+    @parameters begin
+        a[1:2], [unit = u"m"]
+    end
+end
+
+@named sys = ArrayParamTest()
+
+@named sys = ArrayParamTest(a = [1.0, 3.0]u"cm")
+@test ModelingToolkit.getdefault(sys.a) ≈ [0.01, 0.03]