diff --git a/runtime/doc/vim_diff.txt b/runtime/doc/vim_diff.txt
index bada506c63..524978f523 100644
--- a/runtime/doc/vim_diff.txt
+++ b/runtime/doc/vim_diff.txt
@@ -366,8 +366,9 @@ Macro/|recording| behavior
   the results of keys from 'keymap'.
 
 Mappings:
-  Creating a mapping for a simplifiable key (e.g. <C-I>) doesn't replace an
+- Creating a mapping for a simplifiable key (e.g. <C-I>) doesn't replace an
   existing mapping for its simplified form (e.g. <Tab>).
+- The rhs of a mapping is not simplified when it is defined.
 
 Motion:
   The |jumplist| avoids useless/phantom jumps.
diff --git a/src/nvim/getchar.c b/src/nvim/getchar.c
index eb78317ee7..1284382fe8 100644
--- a/src/nvim/getchar.c
+++ b/src/nvim/getchar.c
@@ -2885,8 +2885,8 @@ void set_maparg_lhs_rhs(const char_u *const orig_lhs, const size_t orig_lhs_len,
       mapargs->rhs_len = 0;
       mapargs->rhs_is_noop = true;
     } else {
-      replaced = replace_termcodes(orig_rhs, orig_rhs_len, &rhs_buf, REPTERM_DO_LT, NULL,
-                                   cpo_flags);
+      replaced = replace_termcodes(orig_rhs, orig_rhs_len, &rhs_buf,
+                                   REPTERM_DO_LT | REPTERM_NO_SIMPLIFY, NULL, cpo_flags);
       mapargs->rhs_len = STRLEN(replaced);
       mapargs->rhs_is_noop = false;
       mapargs->rhs = xcalloc(mapargs->rhs_len + 1, sizeof(char_u));
@@ -4861,15 +4861,21 @@ char_u *getcmdkeycmd(int promptc, void *cookie, int indent, bool do_concat)
       // special case to give nicer error message
       emsg(e_cmdmap_repeated);
       aborted = true;
-    } else if (IS_SPECIAL(c1)) {
-      if (c1 == K_SNR) {
-        ga_concat(&line_ga, "<SNR>");
-      } else {
-        semsg(e_cmdmap_key, get_special_key_name(c1, cmod));
-        aborted = true;
-      }
+    } else if (c1 == K_SNR) {
+      ga_concat(&line_ga, "<SNR>");
     } else {
-      ga_append(&line_ga, (char)c1);
+      if (cmod != 0) {
+        ga_append(&line_ga, (char)K_SPECIAL);
+        ga_append(&line_ga, (char)KS_MODIFIER);
+        ga_append(&line_ga, (char)cmod);
+      }
+      if (IS_SPECIAL(c1)) {
+        ga_append(&line_ga, (char)K_SPECIAL);
+        ga_append(&line_ga, (char)K_SECOND(c1));
+        ga_append(&line_ga, (char)K_THIRD(c1));
+      } else {
+        ga_append(&line_ga, (char)c1);
+      }
     }
 
     cmod = 0;
diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index 5983f18bb5..070d96ebb3 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -997,8 +997,8 @@ EXTERN char e_float_as_string[] INIT(= N_("E806: using Float as a String"));
 
 EXTERN char e_autocmd_err[] INIT(= N_("E5500: autocmd has thrown an exception: %s"));
 EXTERN char e_cmdmap_err[] INIT(= N_("E5520: <Cmd> mapping must end with <CR>"));
-EXTERN char e_cmdmap_repeated[] INIT(= N_("E5521: <Cmd> mapping must end with <CR> before second <Cmd>"));
-EXTERN char e_cmdmap_key[] INIT(= N_("E5522: <Cmd> mapping must not include %s key"));
+EXTERN char e_cmdmap_repeated[]
+INIT(= N_("E5521: <Cmd> mapping must end with <CR> before second <Cmd>"));
 
 EXTERN char e_api_error[] INIT(= N_("E5555: API call: %s"));
 
diff --git a/test/functional/ex_cmds/cmd_map_spec.lua b/test/functional/ex_cmds/cmd_map_spec.lua
index 64cf53dfa9..dbbfadabd8 100644
--- a/test/functional/ex_cmds/cmd_map_spec.lua
+++ b/test/functional/ex_cmds/cmd_map_spec.lua
@@ -93,19 +93,6 @@ describe('mappings with <Cmd>', function()
       {2:E5521: <Cmd> mapping must end with <CR> before second <Cmd>}      |
     ]])
 
-    command('noremap <F3> <Cmd><F3>let x = 2<cr>')
-    feed('<F3>')
-    screen:expect([[
-      ^some short lines                                                 |
-      of test text                                                     |
-      {1:~                                                                }|
-      {1:~                                                                }|
-      {1:~                                                                }|
-      {1:~                                                                }|
-      {1:~                                                                }|
-      {2:E5522: <Cmd> mapping must not include <F3> key}                   |
-    ]])
-
     command('noremap <F3> <Cmd>let x = 3')
     feed('<F3>')
     screen:expect([[
@@ -121,6 +108,34 @@ describe('mappings with <Cmd>', function()
     eq(0, eval('x'))
   end)
 
+  it('allows special keys and modifiers', function()
+    command('noremap <F3> <Cmd>normal! <Down><CR>')
+    feed('<F3>')
+    screen:expect([[
+      some short lines                                                 |
+      ^of test text                                                     |
+      {1:~                                                                }|
+      {1:~                                                                }|
+      {1:~                                                                }|
+      {1:~                                                                }|
+      {1:~                                                                }|
+                                                                       |
+    ]])
+
+    command('noremap <F3> <Cmd>normal! <C-Right><CR>')
+    feed('<F3>')
+    screen:expect([[
+      some short lines                                                 |
+      of ^test text                                                     |
+      {1:~                                                                }|
+      {1:~                                                                }|
+      {1:~                                                                }|
+      {1:~                                                                }|
+      {1:~                                                                }|
+                                                                       |
+    ]])
+  end)
+
   it('works in various modes and sees correct `mode()` value', function()
     -- normal mode
     feed('<F3>')
diff --git a/test/functional/ui/input_spec.lua b/test/functional/ui/input_spec.lua
index 0f4e97088c..07582ba602 100644
--- a/test/functional/ui/input_spec.lua
+++ b/test/functional/ui/input_spec.lua
@@ -313,6 +313,11 @@ it('unsimplified mapping works when there was a partial match vim-patch:8.2.4504
   expect('xb')
 end)
 
+it('rhs of a mapping is not simplified', function()
+  command('nnoremap <Plug>foo <C-J>')
+  eq('<C-J>', funcs.maparg('<Plug>foo'))
+end)
+
 describe('input non-printable chars', function()
   after_each(function()
     os.remove('Xtest-overwrite')