diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9f4e5972..f417f7ba 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -97,7 +97,7 @@
 - Dev: Fixed incorrect lua generation of static methods for typescript plugins. (#6190, #6223)
 - Dev: Merged top/bottom and left/right notebook layouts. (#6215)
 - Dev: Refactored `Button` and friends. (#6102, #6255, #6266, #6302, #6268, #6334, #6371, #6372)
-- Dev: Made "add split" button (part of the split header) a natively rendered button. (#6349)
+- Dev: Made "add split" button (part of the split header) a natively rendered button. (#6349, #6385)
 - Dev: Made Settings & Account button on Linux/macOS SVGs. (#6267)
 - Dev: Made "Chatters" button an SVG. (#6397)
 - Dev: Made "Moderation" button an SVG. (#6398, #6412, #6414)
diff --git a/src/widgets/Notebook.cpp b/src/widgets/Notebook.cpp
index f70d9417..7aa08b01 100644
--- a/src/widgets/Notebook.cpp
+++ b/src/widgets/Notebook.cpp
@@ -705,7 +705,7 @@ void Notebook::setShowAddButton(bool value)
 
 void Notebook::resizeAddButton()
 {
-    float h = (NOTEBOOK_TAB_HEIGHT - 1) * this->scale();
+    int h = static_cast<int>((NOTEBOOK_TAB_HEIGHT - 1) * this->scale());
     this->addButton_->setFixedSize(h, h);
 }
 
diff --git a/src/widgets/buttons/DrawnButton.cpp b/src/widgets/buttons/DrawnButton.cpp
index 3e28149e..afa2da5e 100644
--- a/src/widgets/buttons/DrawnButton.cpp
+++ b/src/widgets/buttons/DrawnButton.cpp
@@ -35,7 +35,7 @@ void DrawnButton::themeChangedEvent()
     switch (this->symbol)
     {
         case Symbol::Plus: {
-            o.padding = 3;
+            o.padding = 4;
             o.thickness = 1;
 
             o.foreground = this->theme->messages.textColors.system;
@@ -107,6 +107,21 @@ void DrawnButton::paintContent(QPainter &painter)
             QRect inner;
             inner.setSize(innerSize);
             inner.moveCenter(this->rect().center());
+            inner = inner.marginsRemoved({padding, padding, padding, padding});
+
+            // make sure that the inner size is always odd:
+            // (width): [====outer====][|inner|][====outer====]
+            // -> 2 * outer_w + inner_w
+            // -> 2 * outer_w + 1dp
+            // -> odd
+            if ((inner.width() % 2) == 0)
+            {
+                inner.setRight(inner.right() + 1);
+            }
+            if ((inner.height() % 2) == 0)
+            {
+                inner.setTop(inner.top() - 1);
+            }
 
             auto top = inner.top();
             auto bottom = inner.bottom();
@@ -114,11 +129,9 @@ void DrawnButton::paintContent(QPainter &painter)
             auto left = inner.left();
             auto right = inner.right();
 
-            QLine vertical(center.x(), top + padding, center.x(),
-                           bottom - padding);
+            QLine vertical(center.x(), top, center.x(), bottom);
             painter.drawLine(vertical);
-            QLine horizontal(left + padding, center.y(), right - padding,
-                             center.y());
+            QLine horizontal(left, center.y(), right, center.y());
             painter.drawLine(horizontal);
         }
         break;
diff --git a/src/widgets/splits/SplitHeader.cpp b/src/widgets/splits/SplitHeader.cpp
index 26740e6a..cabe695d 100644
--- a/src/widgets/splits/SplitHeader.cpp
+++ b/src/widgets/splits/SplitHeader.cpp
@@ -1101,9 +1101,10 @@ void SplitHeader::themeChangedEvent()
     }
     this->titleLabel_->setPalette(palette);
 
+    auto bg = this->theme->splits.header.background;
     this->addButton_->setOptions({
-        .background = this->theme->messages.backgrounds.regular,
-        .backgroundHover = this->theme->messages.backgrounds.regular,
+        .background = bg,
+        .backgroundHover = bg,
     });
 
     this->update();