diff --git a/src/nvim/highlight.c b/src/nvim/highlight.c
index 88bf5dbd6e..a0114bbbe8 100644
--- a/src/nvim/highlight.c
+++ b/src/nvim/highlight.c
@@ -374,10 +374,15 @@ void update_window_hl(win_T *wp, bool invalid)
       if (wp->w_float_config.border_hl_ids[i]) {
         attr = hl_get_ui_attr(ns_id, HLF_BORDER,
                               wp->w_float_config.border_hl_ids[i], false);
-        HlAttrs a = syn_attr2entry(attr);
-        if (a.hl_blend) {
-          wp->w_float_config.shadow = true;
-        }
+      }
+      HlAttrs a = syn_attr2entry(attr);
+      if (a.hl_blend == -1 && wp->w_p_winbl > 0) {
+        HlEntry entry = attr_entry(attr);
+        a.hl_blend = entry.attr.hl_blend = (int)wp->w_p_winbl;
+        attr = get_attr_entry(entry);
+      }
+      if (a.hl_blend > 0) {
+        wp->w_float_config.shadow = true;
       }
       wp->w_float_config.border_attr[i] = attr;
     }
diff --git a/src/nvim/option.c b/src/nvim/option.c
index 7005b63cac..690a03f1a0 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -2686,7 +2686,7 @@ static const char *did_set_winblend(optset_T *args)
   if (value != old_value) {
     win->w_p_winbl = MAX(MIN(win->w_p_winbl, 100), 0);
     win->w_hl_needs_update = true;
-    check_blending(curwin);
+    check_blending(win);
   }
 
   return NULL;
diff --git a/test/functional/ui/float_spec.lua b/test/functional/ui/float_spec.lua
index f9849ea7fa..c9f28f430a 100644
--- a/test/functional/ui/float_spec.lua
+++ b/test/functional/ui/float_spec.lua
@@ -1017,7 +1017,7 @@ describe('float window', function()
           {1:               }|
           {2:~              }|
         ]], float_pos={
-          [5] = {{id = 1002}, "NW", 4, 2, 10, true, 50};
+          [5] = {{id = 1002}, "NW", 4, 2, 10, true};
         }}
       else
         screen:expect([[
@@ -9191,6 +9191,13 @@ describe('float window', function()
         [13] = {background = Screen.colors.LightGray, blend = 30},
         [14] = {foreground = Screen.colors.Grey0, background = Screen.colors.Grey88},
         [15] = {foreground = tonumber('0x939393'), background = Screen.colors.Grey88},
+        [16] = {background = Screen.colors.Grey90};
+        [17] = {blend = 100};
+        [18] = {background = Screen.colors.LightMagenta, blend = 100};
+        [19] = {background = Screen.colors.LightMagenta, bold = true, blend = 100, foreground = Screen.colors.Blue1};
+        [20] = {background = Screen.colors.White, foreground = Screen.colors.Gray0};
+        [21] = {background = Screen.colors.White, bold = true, foreground = tonumber('0x00007f')};
+        [22] = {background = Screen.colors.Gray90, foreground = Screen.colors.Gray0};
       })
       insert([[
         Lorem ipsum dolor sit amet, consectetur
@@ -9321,9 +9328,7 @@ describe('float window', function()
           {13:test           }|
           {13:               }|
           {13:popup    text  }|
-        ]], float_pos={
-          [4] = {{id = 1001}, "NW", 1, 2, 5, true, 50};
-        }}
+        ]], float_pos={[4] = {{id = 1001}, "NW", 1, 2, 5, true}}}
       else
         screen:expect([[
           Ut enim ad minim veniam, quis nostrud             |
@@ -9477,6 +9482,56 @@ describe('float window', function()
                                                             |
         ]])
       end
+
+      -- Check that 'winblend' applies to border
+      meths.win_set_config(win, {border='single'})
+      meths.set_option_value('winblend', 100, {win=win.id})
+      meths.set_option_value("cursorline", true, {win=0})
+      command('hi clear VertSplit')
+      feed('k0')
+      if multigrid then
+        screen:expect{grid=[[
+        ## grid 1
+          [2:--------------------------------------------------]|
+          [2:--------------------------------------------------]|
+          [2:--------------------------------------------------]|
+          [2:--------------------------------------------------]|
+          [2:--------------------------------------------------]|
+          [2:--------------------------------------------------]|
+          [2:--------------------------------------------------]|
+          [2:--------------------------------------------------]|
+          [3:--------------------------------------------------]|
+        ## grid 2
+          Ut enim ad minim veniam, quis nostrud             |
+          exercitation ullamco laboris nisi ut aliquip ex   |
+          ea commodo consequat. Duis aute irure dolor in    |
+          reprehenderit in voluptate velit esse cillum      |
+          dolore eu fugiat nulla pariatur. Excepteur sint   |
+          occaecat cupidatat non proident, sunt in culpa    |
+          {16:^qui officia deserunt mollit anim id est           }|
+          laborum.                                          |
+        ## grid 3
+                                                            |
+        ## grid 4
+          {17:┌───────────────┐}|
+          {17:│}{11:popup    text}{18:  }{17:│}|
+          {17:│}{19:~              }{17:│}|
+          {17:│}{19:~              }{17:│}|
+          {17:└───────────────┘}|
+        ]], float_pos={[4] = {{id = 1001}, "NW", 1, 2, 5, true}}}
+      else
+        screen:expect([[
+          Ut enim ad minim veniam, quis nostrud             |
+          exercitation ullamco laboris nisi ut aliquip ex   |
+          ea co{20:┌───────────────┐}Duis aute irure dolor in    |
+          repre{20:│}{5:popup}{6:it i}{5:text}{20:lu│}tate velit esse cillum      |
+          dolor{20:│}{21:~}{20:eu fugiat null│} pariatur. Excepteur sint   |
+          occae{20:│}{21:~}{20:t cupidatat no│} proident, sunt in culpa    |
+          {16:^qui o}{22:└───────────────┘}{16:ollit anim id est           }|
+          laborum.                                          |
+                                                            |
+        ]])
+      end
     end)
 
     it('can overlap doublewidth chars', function()