diff --git a/src/testdir/test_method.vim b/src/testdir/test_method.vim
index 8c5f35b..69adc30 100644
--- a/src/testdir/test_method.vim
+++ b/src/testdir/test_method.vim
@@ -8,6 +8,7 @@
   eval l->assert_notequal([3, 2, 1])
   eval l->assert_notequal([3, 2, 1], 'wrong')
   call assert_equal(l, l->copy())
+  call assert_equal(l, l->deepcopy())
   call assert_equal(1, l->count(2))
   call assert_false(l->empty())
   call assert_true([]->empty())
@@ -38,6 +39,7 @@
   let d = #{one: 1, two: 2, three: 3}
 
   call assert_equal(d, d->copy())
+  call assert_equal(d, d->deepcopy())
   call assert_equal(1, d->count(2))
   call assert_false(d->empty())
   call assert_true({}->empty())