diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index 03ab2a76ad..058b36b8f4 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -1609,14 +1609,16 @@ static void init_prompt(int cmdchar_todo)
     // prompt is missing, insert it or append a line with it
     if (*text == NUL) {
       ml_replace(curbuf->b_prompt_start.mark.lnum, prompt, true);
+      inserted_bytes(curbuf->b_prompt_start.mark.lnum, 0, 0, prompt_len);
     } else {
-      ml_append(curbuf->b_ml.ml_line_count, prompt, 0, false);
+      const linenr_T lnum = curbuf->b_ml.ml_line_count;
+      ml_append(lnum, prompt, 0, false);
+      appended_lines_mark(lnum, 1);
       curbuf->b_prompt_start.mark.lnum = curbuf->b_ml.ml_line_count;
     }
     curbuf->b_prompt_start.mark.col = prompt_len;
     curwin->w_cursor.lnum = curbuf->b_ml.ml_line_count;
     coladvance(curwin, MAXCOL);
-    inserted_bytes(curbuf->b_ml.ml_line_count, 0, 0, (colnr_T)prompt_len);
   }
 
   // Insert always starts after the prompt, allow editing text after it.
diff --git a/test/functional/api/extmark_spec.lua b/test/functional/api/extmark_spec.lua
index 65a1f9ccd3..50dd566489 100644
--- a/test/functional/api/extmark_spec.lua
+++ b/test/functional/api/extmark_spec.lua
@@ -1603,6 +1603,15 @@ describe('API/extmarks', function()
     eq('invalid', get_extmark_range(marks[3]))
     eq('invalid', get_extmark_range(marks[4]))
     eq({ 0, 10, 1, 0 }, get_extmark_range(marks[5]))
+
+    feed('hello')
+    eq({ 0, 15 }, get_extmark_range(marks[1]))
+    eq({ 0, 15, 1, 0 }, get_extmark_range(marks[5]))
+    -- init_prompt uses correct range for inserted_bytes when fixing empty prompt.
+    fn.setline('.', { '', 'last line' })
+    eq({ 'discard > ', 'last line' }, api.nvim_buf_get_lines(0, 0, -1, true))
+    eq({ 0, 10 }, get_extmark_range(marks[1]))
+    eq({ 0, 10, 1, 0 }, get_extmark_range(marks[5]))
   end)
 
   it('can get details', function()
diff --git a/test/functional/lua/buffer_updates_spec.lua b/test/functional/lua/buffer_updates_spec.lua
index e884499a98..e87407f176 100644
--- a/test/functional/lua/buffer_updates_spec.lua
+++ b/test/functional/lua/buffer_updates_spec.lua
@@ -463,6 +463,14 @@ describe('lua: nvim_buf_attach on_lines', function()
       { 'test1', 'lines', 1, 12, 0, 1, 1, 16 },
     }
     eq({ 'foo > hello', 'there' }, api.nvim_buf_get_lines(0, 0, -1, true))
+
+    -- init_prompt uses appended_lines_mark when appending to fix prompt.
+    api.nvim_buf_set_lines(0, 0, -1, true, { 'hi' })
+    eq({ 'hi', 'foo > ' }, api.nvim_buf_get_lines(0, 0, -1, true))
+    check_events {
+      { 'test1', 'lines', 1, 13, 0, 2, 1, 18 },
+      { 'test1', 'lines', 1, 14, 1, 1, 2, 0 },
+    }
   end)
 end)
 
@@ -1652,6 +1660,14 @@ describe('lua: nvim_buf_attach on_bytes', function()
         { 'test1', 'bytes', 1, 15, 2, 0, 6, 0, 10, 10, 0, 7, 7 },
       }
       eq({ '% ', '% ', 'cool > sup', 'dood' }, api.nvim_buf_get_lines(0, 0, -1, true))
+
+      -- init_prompt uses appended_lines_mark when appending to fix prompt.
+      api.nvim_buf_set_lines(0, 0, -1, true, { 'hi' })
+      eq({ 'hi', 'cool > ' }, api.nvim_buf_get_lines(0, 0, -1, true))
+      check_events {
+        { 'test1', 'bytes', 1, 16, 0, 0, 0, 4, 0, 22, 1, 0, 3 },
+        { 'test1', 'bytes', 1, 17, 1, 0, 3, 0, 0, 0, 1, 0, 8 },
+      }
     end)
 
     local function test_lockmarks(mode)