diff --git a/src/testdir/test_textprop.vim b/src/testdir/test_textprop.vim
index 32001b3..6dbaa53 100644
--- a/src/testdir/test_textprop.vim
+++ b/src/testdir/test_textprop.vim
@@ -6,8 +6,6 @@
 
 source screendump.vim
 
-" test length zero
-
 func Test_proptype_global()
   call prop_type_add('comment', {'highlight': 'Directory', 'priority': 123, 'start_incl': 1, 'end_incl': 1})
   let proptypes = prop_type_list()
@@ -233,13 +231,20 @@
 
   " Prop without length or end column is zero length
   call prop_clear(1)
-  call prop_add(1, 5, {'type': 'two'})
-  let expected = [{'col': 5, 'length': 0, 'type': 'two', 'id': 0, 'start': 1, 'end': 1}]
+  call prop_type_add('included', {'start_incl': 1, 'end_incl': 1})
+  call prop_add(1, 5, #{type: 'included'})
+  let expected = [#{col: 5, length: 0, type: 'included', id: 0, start: 1, end: 1}]
+  call assert_equal(expected, prop_list(1))
+
+  " Inserting text makes the prop bigger.
+  exe "normal 5|ixx\<Esc>"
+  let expected = [#{col: 5, length: 2, type: 'included', id: 0, start: 1, end: 1}]
   call assert_equal(expected, prop_list(1))
 
   call assert_fails("call prop_add(1, 5, {'type': 'two', 'bufnr': 234343})", 'E158:')
 
   call DeletePropTypes()
+  call prop_type_delete('included')
   bwipe!
 endfunc