diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
index a58b03b6b..da5b2a697 100644
--- a/docs/CHANGELOG.txt
+++ b/docs/CHANGELOG.txt
@@ -98,6 +98,8 @@ Other Changes:
     end of storage when trailing items are unselected (#9604) [@MilosLord]
 - Drags: fixed handling of `ImGuiSliderFlags_WrapAround`: value could temporarily
   escape the range when dragging fast. (#9612, #9611, #7749) [@swayie, @ocornut]
+- Checkbox: indeterminate/mixed value inner rectangle never has rounding,
+  to reduce confusion with a radio button. (#5518, #5677, #6865, #2644)
 - ColorEdit:
   - ColorButton, ColorEdit, ColorPicker: fixed an issue rendering colors when
     inside a `BeginDisabled(false)` block, caused by the alpha cancelling-out
diff --git a/imgui_widgets.cpp b/imgui_widgets.cpp
index 91f0d0f61..3d3d1f008 100644
--- a/imgui_widgets.cpp
+++ b/imgui_widgets.cpp
@@ -1299,8 +1299,9 @@ bool ImGui::Checkbox(const char* label, bool* v)
         {
             // Undocumented tristate/mixed/indeterminate checkbox (#2644)
             // This may seem awkwardly designed because the aim is to make ImGuiItemFlags_MixedValue supported by all widgets (not just checkbox)
-            ImVec2 pad(ImMax(1.0f, IM_TRUNC(square_sz / 3.6f)), ImMax(1.0f, IM_TRUNC(square_sz / 3.6f)));
-            window->DrawList->AddRectFilled(check_bb.Min + pad, check_bb.Max - pad, check_col, style.FrameRounding);
+            const float pad = ImMax(1.0f, IM_TRUNC(square_sz / 3.6f));
+            const float rounding = 0.0f;// IM_TRUNC(ImMin((square_sz - pad * 2.0f) * 0.20f, style.FrameRounding)); // Clamp rounding
+            window->DrawList->AddRectFilled(check_bb.Min + ImVec2(pad, pad), check_bb.Max - ImVec2(pad, pad), check_col, rounding);
         }
         else if (*v)
         {