diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index c5e25b4acd..da7da8c220 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -581,6 +581,10 @@ static int insert_execute(VimState *state, int key)
         return 1;  // continue
       }
 
+      if (p_ac) {
+        ins_compl_set_autocomplete(true);
+      }
+
       // A non-white character that fits in with the current
       // completion: Add to "compl_leader".
       if (ins_compl_accept_char(s->c)) {
@@ -598,6 +602,10 @@ static int insert_execute(VimState *state, int key)
         return 1;  // continue
       }
 
+      if (p_ac) {
+        ins_compl_set_autocomplete(false);
+      }
+
       // Pressing CTRL-Y selects the current match.  When
       // compl_enter_selects is set the Enter key does the same.
       if ((s->c == Ctrl_Y
@@ -849,10 +857,11 @@ static int insert_handle_key(InsertState *s)
     auto_format(false, true);
     if (s->did_backspace && p_ac && !char_avail() && curwin->w_cursor.col > 0) {
       s->c = char_before_cursor();
-      if (ins_compl_setup_autocompl(s->c)) {
+      if (vim_isprintc(s->c)) {
         redraw_later(curwin, UPD_VALID);
         update_screen();  // Show char deletion immediately
         ui_flush();
+        ins_compl_set_autocomplete(true);
         insert_do_complete(s);  // Trigger autocompletion
         return 1;
       }
@@ -1233,10 +1242,11 @@ normalchar:
     // closed fold.
     foldOpenCursor();
     // Trigger autocompletion
-    if (p_ac && !char_avail() && ins_compl_setup_autocompl(s->c)) {
+    if (p_ac && !char_avail() && vim_isprintc(s->c)) {
       redraw_later(curwin, UPD_VALID);
       update_screen();  // Show character immediately
       ui_flush();
+      ins_compl_set_autocomplete(true);
       insert_do_complete(s);
     }
 
diff --git a/src/nvim/insexpand.c b/src/nvim/insexpand.c
index af7cc6aae2..87c4487965 100644
--- a/src/nvim/insexpand.c
+++ b/src/nvim/insexpand.c
@@ -6027,6 +6027,7 @@ int ins_complete(int c, bool enable_pum)
 
   if (!compl_started) {
     if (ins_compl_start() == FAIL) {
+      compl_autocomplete = false;
       return FAIL;
     }
   } else if (insert_match && stop_arrow() == FAIL) {
@@ -6109,19 +6110,15 @@ int ins_complete(int c, bool enable_pum)
   }
   compl_was_interrupted = compl_interrupted;
   compl_interrupted = false;
+  compl_autocomplete = false;
 
   return OK;
 }
 
-/// Returns true if the given character 'c' can be used to trigger
-/// autocompletion.
-bool ins_compl_setup_autocompl(int c)
+/// Enable/disable autocompletion
+void ins_compl_set_autocomplete(bool value)
 {
-  if (vim_isprintc(c)) {
-    compl_autocomplete = true;
-    return true;
-  }
-  return false;
+  compl_autocomplete = value;
 }
 
 /// Remove (if needed) and show the popup menu
diff --git a/test/functional/editor/completion_spec.lua b/test/functional/editor/completion_spec.lua
index 130914bb29..49fcf18ac1 100644
--- a/test/functional/editor/completion_spec.lua
+++ b/test/functional/editor/completion_spec.lua
@@ -1417,6 +1417,14 @@ describe('completion', function()
       set autocomplete
     ]])
     screen:try_resize(60, 10)
+    screen:expect([[
+      ^foo                                                         |
+      foobar                                                      |
+      foobarbaz                                                   |
+      {1:~                                                           }|*6
+                                                                  |
+    ]])
+    screen.timeout = 200
 
     feed('Gof')
     screen:expect([[
@@ -1501,6 +1509,57 @@ describe('completion', function()
       {5:-- Keyword completion (^N^P) }{6:match 1 of 3}                   |
     ]])
 
+    -- After the menu is open, ^N/^P and Up/Down should not delay
+    feed('<Esc>')
+    command('set completeopt=menu')
+    feed('Sf')
+    screen:expect([[
+      foo                                                         |
+      foobar                                                      |
+      foobarbaz                                                   |
+      f^                                                           |
+      {1:~                                                           }|*5
+      {5:-- INSERT --}                                                |
+    ]])
+    vim.uv.sleep(500)
+    feed('<C-N>')
+    screen:expect([[
+      foo                                                         |
+      foobar                                                      |
+      foobarbaz                                                   |
+      foobarbaz^                                                   |
+      {12:foobarbaz      }{1:                                             }|
+      {4:foobar         }{1:                                             }|
+      {4:foo            }{1:                                             }|
+      {1:~                                                           }|*2
+      {5:-- INSERT --}                                                |
+    ]])
+    feed('<Down>')
+    screen:expect([[
+      foo                                                         |
+      foobar                                                      |
+      foobarbaz                                                   |
+      foobarbaz^                                                   |
+      {4:foobarbaz      }{1:                                             }|
+      {12:foobar         }{1:                                             }|
+      {4:foo            }{1:                                             }|
+      {1:~                                                           }|*2
+      {5:-- INSERT --}                                                |
+    ]])
+
+    -- When menu is not open Up/Down moves cursor to different line
+    feed('<Esc>Sf')
+    screen:expect([[
+      foo                                                         |
+      foobar                                                      |
+      foobarbaz                                                   |
+      f^                                                           |
+      {1:~                                                           }|*5
+      {5:-- INSERT --}                                                |
+    ]])
+    feed('<Down>')
+    screen:expect_unchanged()
+
     feed('<esc>')
   end)
 end)
diff --git a/test/old/testdir/test_ins_complete.vim b/test/old/testdir/test_ins_complete.vim
index aa36147edc..8804921f7d 100644
--- a/test/old/testdir/test_ins_complete.vim
+++ b/test/old/testdir/test_ins_complete.vim
@@ -5471,7 +5471,7 @@ func Test_autocomplete_timer()
   call assert_equal(['abc', 'ab'], b:matches->mapnew('v:val.word'))
   call assert_equal(0, b:selected)
   call assert_equal(1, g:CallCount)
-  call assert_equal('abc', getline(4))
+  call assert_equal('ab', getline(4))
   set completeopt&
 
   " Test 8: {func} completes after space, but not '.'
@@ -5603,6 +5603,20 @@ func Test_autocompletedelay()
   call term_sendkeys(buf, "Sf\<C-N>")
   call VerifyScreenDump(buf, 'Test_autocompletedelay_7', {})
 
+  " After the menu is open, ^N/^P and Up/Down should not delay
+  call term_sendkeys(buf, "\<Esc>:set completeopt=menu noruler\<CR>")
+  call term_sendkeys(buf, "\<Esc>Sf")
+  sleep 500ms
+  call term_sendkeys(buf, "\<C-N>")
+  call VerifyScreenDump(buf, 'Test_autocompletedelay_8', {})
+  call term_sendkeys(buf, "\<Down>")
+  call VerifyScreenDump(buf, 'Test_autocompletedelay_9', {})
+
+  " When menu is not open Up/Down moves cursor to different line
+  call term_sendkeys(buf, "\<Esc>Sf")
+  call term_sendkeys(buf, "\<Down>")
+  call VerifyScreenDump(buf, 'Test_autocompletedelay_10', {})
+
   call term_sendkeys(buf, "\<esc>")
   call StopVimInTerminal(buf)
 endfunc