diff --git a/src/nvim/drawscreen.c b/src/nvim/drawscreen.c
index bf2bc077e0..5201923a96 100644
--- a/src/nvim/drawscreen.c
+++ b/src/nvim/drawscreen.c
@@ -1705,7 +1705,8 @@ static void win_update(win_T *wp)
   // incurring scrolling even though wp->w_topline is still the same.
   // Compare against an adjusted topline instead:
   linenr_T topline_conceal = wp->w_topline;
-  while (decor_conceal_line(wp, topline_conceal - 1, false)) {
+  while (topline_conceal < buf->b_ml.ml_line_count
+         && decor_conceal_line(wp, topline_conceal - 1, false)) {
     topline_conceal++;
     hasFolding(wp, topline_conceal, NULL, &topline_conceal);
   }
@@ -2320,6 +2321,7 @@ static void win_update(win_T *wp)
 
         // Adjust "wl_lastlnum" for concealed lines below the last line in the window.
         while (row == wp->w_grid.rows
+               && wp->w_lines[idx].wl_lastlnum < buf->b_ml.ml_line_count
                && decor_conceal_line(wp, wp->w_lines[idx].wl_lastlnum, false)) {
           wp->w_lines[idx].wl_lastlnum++;
           hasFolding(wp, wp->w_lines[idx].wl_lastlnum, NULL, &wp->w_lines[idx].wl_lastlnum);
diff --git a/src/nvim/mouse.c b/src/nvim/mouse.c
index 984f746add..abc2137bc2 100644
--- a/src/nvim/mouse.c
+++ b/src/nvim/mouse.c
@@ -1661,7 +1661,8 @@ bool mouse_comp_pos(win_T *win, int *rowp, int *colp, linenr_T *lnump)
   }
 
   // Mouse row reached, adjust lnum for concealed lines.
-  while (decor_conceal_line(win, lnum - 1, false)) {
+  while (lnum < win->w_buffer->b_ml.ml_line_count
+         && decor_conceal_line(win, lnum - 1, false)) {
     lnum++;
     hasFolding(win, lnum, NULL, &lnum);
   }
diff --git a/test/functional/ui/mouse_spec.lua b/test/functional/ui/mouse_spec.lua
index 8d7b0cac86..da9a6e5ff9 100644
--- a/test/functional/ui/mouse_spec.lua
+++ b/test/functional/ui/mouse_spec.lua
@@ -2086,8 +2086,15 @@ describe('ui/mouse/input', function()
   it('below a concealed line #33450', function()
     api.nvim_set_option_value('conceallevel', 2, {})
     api.nvim_buf_set_extmark(0, api.nvim_create_namespace(''), 1, 0, { conceal_lines = '' })
-    api.nvim_input_mouse('right', 'press', '', 0, 1, 0)
-    api.nvim_input_mouse('right', 'release', '', 0, 1, 0)
+    api.nvim_input_mouse('left', 'press', '', 0, 1, 0)
+    api.nvim_input_mouse('left', 'release', '', 0, 1, 0)
     eq(3, fn.line('.'))
+    -- No error when clicking below last line that is concealed.
+    screen:try_resize(80, 10) -- Prevent hit-enter
+    api.nvim_set_option_value('cmdheight', 3, {})
+    local count = api.nvim_buf_line_count(0)
+    api.nvim_buf_set_extmark(0, 1, count - 1, 0, { conceal_lines = '' })
+    api.nvim_input_mouse('left', 'press', '', 0, count, 0)
+    eq('', api.nvim_get_vvar('errmsg'))
   end)
 end)