diff --git a/test/test_args.jl b/test/test_args.jl
index e63b17d2..709136d5 100644
--- a/test/test_args.jl
+++ b/test/test_args.jl
@@ -1,8 +1,8 @@
 using Plots, Test
 
 @testset "Series Attributes" begin
-    pl = plot([1, 2, 3], lw = 5)
-    @test hline!(pl, [1.75]).series_list == hline!(pl, [1.75], z_order = :front).series_list
-    @test hline!(pl, [1.75], z_order = :back)[1].series_list[1][:label] == "y3"
-    @test hline!(pl, [1.75], z_order = 2)[1].series_list[2][:label] == "y3"
+    pl = plot([[1, 2, 3], [2, 3, 4]], lw = 5)
+    @test hline!(deepcopy(pl), [1.75])[1].series_list[3][:label] == hline!(deepcopy(pl), [1.75], z_order = :front)[1].series_list[3][:label] == "y3"
+    @test hline!(deepcopy(pl), [1.75], z_order = :back)[1].series_list[1][:label] == "y3"
+    @test hline!(deepcopy(pl), [1.75], z_order = 2)[1].series_list[2][:label] == "y3"
 end