diff --git a/.github/workflows/Downstream.yml b/.github/workflows/Downstream.yml
index 87149aa..12b3ff0 100644
--- a/.github/workflows/Downstream.yml
+++ b/.github/workflows/Downstream.yml
@@ -29,8 +29,6 @@ jobs:
   test:
     name: ${{ matrix.package.repo }}/${{ matrix.julia-version }}
     runs-on: ${{ matrix.os }}
-    env:
-      GROUP: ${{ matrix.package.group }}
     strategy:
       fail-fast: false
       matrix:
diff --git a/Project.toml b/Project.toml
index ac3c3f2..f57b78b 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "QuestBase"
 uuid = "7e80f742-43d6-403d-a9ea-981410111d43"
 authors = ["Orjan Ameye <orjan.ameye@hotmail.com>", "Jan Kosata <kosataj@phys.ethz.ch>", "Javier del Pino <jdelpino@phys.ethz.ch>"]
-version = "0.3.2"
+version = "0.3.3"
 
 [deps]
 DocStringExtensions = "ffbed154-4ef7-542d-bbb7-c09d3a79fcae"
diff --git a/src/DifferentialEquation.jl b/src/DifferentialEquation.jl
index 26195bc..fcda18c 100644
--- a/src/DifferentialEquation.jl
+++ b/src/DifferentialEquation.jl
@@ -32,6 +32,10 @@ mutable struct DifferentialEquation
         return new(eqs, OrderedDict(var => OrderedSet() for var in keys(eqs)))
     end
 
+    function DifferentialEquation()
+        return new(OrderedDict{Num,Equation}(), OrderedDict{Num,OrderedSet{Num}}())
+    end
+
     # uses the above constructor if no harmonics defined
     function DifferentialEquation(eqs::Vector{Equation}, vars::Vector{Num})
         if length(eqs) != length(vars)
diff --git a/src/HarmonicEquation.jl b/src/HarmonicEquation.jl
index b1bd846..cb8348a 100644
--- a/src/HarmonicEquation.jl
+++ b/src/HarmonicEquation.jl
@@ -19,7 +19,11 @@ mutable struct HarmonicEquation
     jacobian::Matrix{Num}
 
     # use a self-referential constructor with _parameters
-    function HarmonicEquation(equations, variables, nat_eq)
+    function HarmonicEquation(
+        equations::Vector{Equation},
+        variables::Vector{HarmonicVariable},
+        nat_eq::DifferentialEquation,
+    )
         return (
             x=new(
                 equations,
@@ -32,7 +36,12 @@ mutable struct HarmonicEquation
             x
         )
     end
-    function HarmonicEquation(equations, variables, parameters, natural_equation)
+    function HarmonicEquation(
+        equations::Vector{Equation},
+        variables::Vector{HarmonicVariable},
+        parameters::Vector{Num},
+        natural_equation::DifferentialEquation,
+    )
         return new(
             equations,
             variables,
@@ -41,6 +50,14 @@ mutable struct HarmonicEquation
             dummy_symbolic_Jacobian(length(variables)),
         )
     end
+    function HarmonicEquation(
+        equations::Vector{Equation},
+        variables::Vector{HarmonicVariable},
+        parameters::Vector{Num},
+        jacobian::Matrix{Num},
+    )
+        return new(equations, variables, parameters, DifferentialEquation(), jacobian)
+    end
 end
 
 "Get the parameters (not time nor variables) of a HarmonicEquation"
diff --git a/test/DifferentialEquations.jl b/test/DifferentialEquations.jl
index c22acb4..79b85bb 100644
--- a/test/DifferentialEquations.jl
+++ b/test/DifferentialEquations.jl
@@ -42,6 +42,11 @@ using QuestBase:
     diff_eq3 = DifferentialEquation(expr, x)
     @test length(diff_eq3.equations) == 1
     @test diff_eq3.equations[x].rhs == 0
+
+    # Test empty constructor
+    diff = DifferentialEquation()
+    @test isempty(diff.equations)
+    @test isempty(diff.harmonics)
 end
 
 @testset "Helper Functions" begin
diff --git a/test/HarmonicEquation.jl b/test/HarmonicEquation.jl
index 2e15e46..9bff61f 100644
--- a/test/HarmonicEquation.jl
+++ b/test/HarmonicEquation.jl
@@ -46,6 +46,9 @@ hv2 = HarmonicVariable(v, "test", "v", Num(1.0), y)
         @test heq.parameters == Num[]
         @test heq.jacobian isa Matrix{Num}
     end
+
+    heq3 = HarmonicEquation([eq1, eq2], [hv1, hv2], Num[], Num[1 1; 1 1])
+    @test isempty(heq3.natural_equation.harmonics)
 end
 
 @testset "Parameter handling" begin