diff --git a/runtime/doc/map.txt b/runtime/doc/map.txt
index ca1ddaabd4..da6a305e89 100644
--- a/runtime/doc/map.txt
+++ b/runtime/doc/map.txt
@@ -1623,11 +1623,11 @@ The valid escape sequences are
 					*<mods>* *<q-mods>* *:command-modifiers*
 	<mods>  The command modifiers, if specified. Otherwise, expands to
 		nothing. Supported modifiers are |:aboveleft|, |:belowright|,
-		|:botright|, |:browse|, |:confirm|, |:hide|, |:keepalt|,
-		|:keepjumps|, |:keepmarks|, |:keeppatterns|, |:leftabove|,
-		|:lockmarks|, |:noautocmd|, |:noswapfile| |:rightbelow|,
-		|:sandbox|, |:silent|, |:tab|, |:topleft|, |:unsilent|,
-		|:verbose|, and |:vertical|.
+		|:botright|, |:browse|, |:confirm|, |:hide|, |:horizontal|,
+		|:keepalt|, |:keepjumps|, |:keepmarks|, |:keeppatterns|,
+		|:leftabove|, |:lockmarks|, |:noautocmd|, |:noswapfile|
+		|:rightbelow|, |:sandbox|, |:silent|, |:tab|, |:topleft|,
+		|:unsilent|, |:verbose|, and |:vertical|.
 		Note that |:filter| is not supported.
 		Examples: >
 		    command! -nargs=+ -complete=file MyEdit
diff --git a/src/nvim/cmdexpand.c b/src/nvim/cmdexpand.c
index 6fc63f72a1..9d8dd197bd 100644
--- a/src/nvim/cmdexpand.c
+++ b/src/nvim/cmdexpand.c
@@ -1203,6 +1203,7 @@ static const char *set_context_by_cmdname(const char *cmd, cmdidx_T cmdidx, cons
   case CMD_folddoclosed:
   case CMD_folddoopen:
   case CMD_hide:
+  case CMD_horizontal:
   case CMD_keepalt:
   case CMD_keepjumps:
   case CMD_keepmarks:
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index f99253ea75..ea21dc8ae7 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -1757,6 +1757,7 @@ static bool skip_cmd(const exarg_T *eap)
     case CMD_filter:
     case CMD_help:
     case CMD_hide:
+    case CMD_horizontal:
     case CMD_ijump:
     case CMD_ilist:
     case CMD_isearch:
diff --git a/src/nvim/testdir/test_cmdline.vim b/src/nvim/testdir/test_cmdline.vim
index 4bfd22cb6c..bc06e70ff4 100644
--- a/src/nvim/testdir/test_cmdline.vim
+++ b/src/nvim/testdir/test_cmdline.vim
@@ -926,6 +926,10 @@ func Test_cmdline_complete_various()
   call feedkeys(":all abc\<C-A>\<C-B>\"\<CR>", 'xt')
   call assert_equal("\"all abc\<C-A>", @:)
 
+  " completion for :wincmd with :horizontal modifier
+  call feedkeys(":horizontal wincm\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal("\"horizontal wincmd", @:)
+
   " completion for a command with a command modifier
   call feedkeys(":topleft new\<C-A>\<C-B>\"\<CR>", 'xt')
   call assert_equal("\"topleft new", @:)
diff --git a/src/nvim/testdir/test_usercommands.vim b/src/nvim/testdir/test_usercommands.vim
index e37fe43b22..1065dd16e2 100644
--- a/src/nvim/testdir/test_usercommands.vim
+++ b/src/nvim/testdir/test_usercommands.vim
@@ -101,6 +101,10 @@ function Test_cmdmods()
   call assert_equal('vertical', g:mods)
   vert MyCmd
   call assert_equal('vertical', g:mods)
+  horizontal MyCmd
+  call assert_equal('horizontal', g:mods)
+  hor MyCmd
+  call assert_equal('horizontal', g:mods)
 
   aboveleft belowright botright browse confirm hide keepalt keepjumps
 	      \ keepmarks keeppatterns lockmarks noautocmd noswapfile silent
diff --git a/src/nvim/usercmd.c b/src/nvim/usercmd.c
index 9cc9fb5588..3726273d28 100644
--- a/src/nvim/usercmd.c
+++ b/src/nvim/usercmd.c
@@ -1247,6 +1247,10 @@ size_t add_win_cmd_modifers(char *buf, const cmdmod_T *cmod, bool *multi_mods)
   if (cmod->cmod_split & WSP_VERT) {
     result += add_cmd_modifier(buf, "vertical", multi_mods);
   }
+  // :horizontal
+  if (cmod->cmod_split & WSP_HOR) {
+    result += add_cmd_modifier(buf, "horizontal", multi_mods);
+  }
   return result;
 }