diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 479b6a24cf..cb0ebf0d6e 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -2777,9 +2777,11 @@ int parse_command_modifiers(exarg_T *eap, const char **errormsg, cmdmod_T *cmod,
         size_t len = strlen(cmd_start);
 
         // Special case: empty command uses "+":
-        //  "'<,'>mods" -> "mods'<,'>+
+        //  "'<,'>mods" -> "mods *+
+        //  Use "*" instead of "'<,'>" to avoid the command getting
+        //  longer, in case is was allocated.
         memmove(orig_cmd, cmd_start, len);
-        strcpy(orig_cmd + len, "'<,'>+");
+        xmemcpyz(orig_cmd + len, S_LEN(" *+"));
       } else {
         memmove(cmd_start - 5, cmd_start, (size_t)(eap->cmd - cmd_start));
         eap->cmd -= 5;
diff --git a/test/old/testdir/test_cmdline.vim b/test/old/testdir/test_cmdline.vim
index f5955a58cf..0a2b7b6141 100644
--- a/test/old/testdir/test_cmdline.vim
+++ b/test/old/testdir/test_cmdline.vim
@@ -2561,6 +2561,14 @@ func Test_cmdwin_insert_mode_close()
   call assert_equal(1, winnr('$'))
 endfunc
 
+func Test_cmdwin_ex_mode_with_modifier()
+  " this was accessing memory after allocated text in Ex mode
+  new
+  call setline(1, ['some', 'text', 'lines'])
+  silent! call feedkeys("gQnormal vq:atopleft\<C-V>\<CR>\<CR>", 'xt')
+  bwipe!
+endfunc
+
 " test that ";" works to find a match at the start of the first line
 func Test_zero_line_search()
   new