diff --git a/Project.toml b/Project.toml
index 3a0203c..8b361ff 100644
--- a/Project.toml
+++ b/Project.toml
@@ -11,7 +11,7 @@ SymbolicUtils = "d1185830-fcd6-423d-90d6-eec64667417b"
 [compat]
 Aqua = "0.8"
 CSV = "0.10.5"
-Catalyst = "14"
+Catalyst = "14, 15"
 DataFrames = "1"
 Downloads = "1"
 ModelingToolkit = "9"
diff --git a/test/systems.jl b/test/systems.jl
index 255ae4d..8f7a9ed 100644
--- a/test/systems.jl
+++ b/test/systems.jl
@@ -3,7 +3,7 @@ using Catalyst, SBML
 using Test
 
 cd(@__DIR__)
-sbmlfile = joinpath("data", "reactionsystem_01.xml")
+sbmlfile = joinpath("test", "data", "reactionsystem_01.xml")
 const IV = default_t()
 @parameters k1, c1
 @species s1(IV), s2(IV), s1s2(IV)
@@ -83,10 +83,11 @@ trueeqs = Equation[default_time_deriv()(s1) ~ k1]
 @test isequal(Catalyst.get_eqs(odesys), trueeqs)
 @test isequal(Catalyst.get_iv(odesys), IV)
 @test isequal(Catalyst.get_unknowns(odesys), [s1])
-@test issetequal(Catalyst.get_ps(odesys), [k1, c1])
+@test issetequal(ModelingToolkit.parameters_toplevel(odesys), [k1, c1])
 u0 = [s1 => 1.0]
 par = [k1 => 1.0, c1 => 2.0]
-@test isequal(ModelingToolkit.defaults(odesys), ModelingToolkit._merge(u0, par))  # PL: @Anand: for some reason this does not work with `Catalyst.get_default()`
+testdef = merge(Dict(u0), Dict(par))
+@test issubset(testdef, defaults(odesys))
 @named odesys = ODESystem(MODEL1)
 isequal(nameof(odesys), :odesys)
 @test structural_simplify(odesys) isa ODESystem
@@ -99,10 +100,11 @@ trueeqs = Equation[default_time_deriv()(s1) ~ -((k1 * s1 * s2) / c1),
 @test isequal(Catalyst.get_eqs(odesys), trueeqs)
 @test isequal(Catalyst.get_iv(odesys), IV)
 @test isequal(Catalyst.get_unknowns(odesys), [s1, s1s2, s2])
-@test issetequal(Catalyst.get_ps(odesys), [k1, c1])
+@test issetequal(Catalyst.parameters_toplevel(odesys), [k1, c1])
 u0 = [s1 => 2 * 1.0, s2 => 2 * 1.0, s1s2 => 2 * 1.0]
 par = [k1 => 1.0, c1 => 2.0]
-@test isequal(ModelingToolkit.defaults(odesys), ModelingToolkit._merge(u0, par))
+testdef = merge(Dict(u0), Dict(par))
+@test issubset(testdef, ModelingToolkit.defaults(odesys))
 @named odesys = ODESystem(MODEL1)
 isequal(nameof(odesys), :odesys)