diff --git a/runtime/doc/api.txt b/runtime/doc/api.txt
index e3063b0591..07e4473ac2 100644
--- a/runtime/doc/api.txt
+++ b/runtime/doc/api.txt
@@ -2841,9 +2841,7 @@ nvim_set_decoration_provider({ns_id}, {*opts})
                  • on_buf: called for each buffer being redrawn (before window
                    callbacks) ["buf", bufnr, tick]
                  • on_win: called when starting to redraw a specific window.
-                   botline_guess is an approximation that does not exceed the
-                   last line number. ["win", winid, bufnr, topline,
-                   botline_guess]
+                   ["win", winid, bufnr, topline, botline]
                  • on_line: called for each buffer line being redrawn. (The
                    interaction with fold lines is subject to change) ["win",
                    winid, bufnr, row]
diff --git a/runtime/lua/vim/_meta/api.lua b/runtime/lua/vim/_meta/api.lua
index c0dfa7635b..02128b66b9 100644
--- a/runtime/lua/vim/_meta/api.lua
+++ b/runtime/lua/vim/_meta/api.lua
@@ -1761,9 +1761,7 @@ function vim.api.nvim_set_current_win(window) end
 ---              • on_buf: called for each buffer being redrawn (before window
 ---                callbacks) ["buf", bufnr, tick]
 ---              • on_win: called when starting to redraw a specific window.
----                botline_guess is an approximation that does not exceed the
----                last line number. ["win", winid, bufnr, topline,
----                botline_guess]
+---                ["win", winid, bufnr, topline, botline]
 ---              • on_line: called for each buffer line being redrawn. (The
 ---                interaction with fold lines is subject to change) ["win",
 ---                winid, bufnr, row]
diff --git a/src/nvim/api/extmark.c b/src/nvim/api/extmark.c
index 0cf16294b6..e66e25e527 100644
--- a/src/nvim/api/extmark.c
+++ b/src/nvim/api/extmark.c
@@ -1009,10 +1009,8 @@ void nvim_buf_clear_namespace(Buffer buffer, Integer ns_id, Integer line_start,
 ///             - on_buf: called for each buffer being redrawn (before
 ///                 window callbacks)
 ///                 ["buf", bufnr, tick]
-///             - on_win: called when starting to redraw a
-///                 specific window. botline_guess is an approximation
-///                 that does not exceed the last line number.
-///                 ["win", winid, bufnr, topline, botline_guess]
+///             - on_win: called when starting to redraw a specific window.
+///                 ["win", winid, bufnr, topline, botline]
 ///             - on_line: called for each buffer line being redrawn.
 ///                 (The interaction with fold lines is subject to change)
 ///                 ["win", winid, bufnr, row]
diff --git a/src/nvim/decoration_provider.c b/src/nvim/decoration_provider.c
index 6a7ecf102d..9bb499fe4b 100644
--- a/src/nvim/decoration_provider.c
+++ b/src/nvim/decoration_provider.c
@@ -15,6 +15,7 @@
 #include "nvim/log.h"
 #include "nvim/lua/executor.h"
 #include "nvim/message.h"
+#include "nvim/move.h"
 #include "nvim/pos_defs.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
@@ -121,10 +122,9 @@ void decor_providers_invoke_win(win_T *wp)
   // then we would need decor_state.running_decor_provider just like "on_line" below
   assert(kv_size(decor_state.active) == 0);
 
-  linenr_T knownmax = MIN(wp->w_buffer->b_ml.ml_line_count,
-                          ((wp->w_valid & VALID_BOTLINE)
-                           ? wp->w_botline
-                           : MAX(wp->w_topline + wp->w_height_inner, wp->w_botline)));
+  if (kv_size(decor_providers) > 0) {
+    validate_botline(wp);
+  }
 
   for (size_t i = 0; i < kv_size(decor_providers); i++) {
     DecorProvider *p = &kv_A(decor_providers, i);
@@ -138,7 +138,7 @@ void decor_providers_invoke_win(win_T *wp)
       ADD_C(args, BUFFER_OBJ(wp->w_buffer->handle));
       // TODO(bfredl): we are not using this, but should be first drawn line?
       ADD_C(args, INTEGER_OBJ(wp->w_topline - 1));
-      ADD_C(args, INTEGER_OBJ(knownmax - 1));
+      ADD_C(args, INTEGER_OBJ(wp->w_botline - 1 - 1));
       if (!decor_provider_invoke((int)i, "win", p->redraw_win, args, true)) {
         kv_A(decor_providers, i).state = kDecorProviderWinDisabled;
       }
diff --git a/test/functional/ui/decorations_spec.lua b/test/functional/ui/decorations_spec.lua
index d78d7d06cc..48df6b3295 100644
--- a/test/functional/ui/decorations_spec.lua
+++ b/test/functional/ui/decorations_spec.lua
@@ -615,9 +615,9 @@ describe('decorations providers', function()
       vim.api.nvim_buf_set_lines(0, 0, -1, false, lines)
     ]])
     setup_provider([[
-      local function on_do(kind, winid, bufnr, topline, botline_guess)
+      local function on_do(kind, winid, bufnr, topline, botline)
         if kind == 'win' then
-          if topline < 100 and botline_guess > 100 then
+          if topline < 100 and botline > 100 then
             api.nvim_buf_set_extmark(bufnr, ns1, 99, -1, { sign_text = 'X' })
           else
             api.nvim_buf_clear_namespace(bufnr, ns1, 0, -1)
@@ -655,7 +655,7 @@ describe('decorations providers', function()
       eok = true
     ]])
     setup_provider([[
-      local function on_do(kind, winid, bufnr, topline, botline_guess)
+      local function on_do(kind, winid, bufnr, topline, botline)
         if kind == 'line' then
           api.nvim_buf_set_extmark(bufnr, ns1, 1, -1, { sign_text = 'X' })
           eok = pcall(api.nvim_buf_clear_namespace, bufnr, ns1, 0, -1)