diff --git a/src/testdir/test_mapping.vim b/src/testdir/test_mapping.vim
index 7f768cf..e886424 100644
--- a/src/testdir/test_mapping.vim
+++ b/src/testdir/test_mapping.vim
@@ -482,6 +482,26 @@
   call assert_match("\tLast set from .*/test_mapping.vim line \\d\\+$",
         \ execute('verbose map ,n')->trim()->split("\n")[1])
 
+  " character with K_SPECIAL byte in rhs
+  nmap foo …
+  call assert_equal(['n  foo           …'],
+        \ execute('nmap foo')->trim()->split("\n"))
+
+  " modified character with K_SPECIAL byte in rhs
+  nmap foo <M-…>
+  call assert_equal(['n  foo           <M-…>'],
+        \ execute('nmap foo')->trim()->split("\n"))
+
+  " character with K_SPECIAL byte in lhs
+  nmap … foo
+  call assert_equal(['n  …             foo'],
+        \ execute('nmap …')->trim()->split("\n"))
+
+  " modified character with K_SPECIAL byte in lhs
+  nmap <M-…> foo
+  call assert_equal(['n  <M-…>         foo'],
+        \ execute('nmap <M-…>')->trim()->split("\n"))
+
   " map to CTRL-V
   exe "nmap ,k \<C-V>"
   call assert_equal(['n  ,k            <Nop>'],