diff --git a/test/sets.jl b/test/sets.jl
index b78d2f15dd989..4d52cb243620c 100644
--- a/test/sets.jl
+++ b/test/sets.jl
@@ -1037,6 +1037,8 @@ end
     @test !isempty(A)
     A = empty!(A)
     @test isempty(A)
+    @test isnothing(sizehint!(A, 10))
+    @test Base.copymutable(A) == copy(A)
 end
 
 @testset "⊊, ⊋" begin