diff --git a/autotests/decorationbuttontest.cpp b/autotests/decorationbuttontest.cpp
--- a/autotests/decorationbuttontest.cpp
+++ b/autotests/decorationbuttontest.cpp
@@ -60,6 +60,8 @@
     void testMenuDoubleClick();
     void testMenuPressAndHold();
     void testApplicationMenu();
+    void testContains_data();
+    void testContains();
 };
 
 void DecorationButtonTest::testButton()
@@ -1342,5 +1344,36 @@
     QCOMPARE(pressedChangedSpy.last().first().toBool(), false);
 }
 
+void DecorationButtonTest::testContains_data()
+{
+    QTest::addColumn<QPointF>("pos");
+    QTest::addColumn<bool>("contains");
+
+    // Button geometry: QRectF(0, 0, 10, 10).
+    QTest::newRow("on left edge")   << QPointF(0, 5)  << true;
+    QTest::newRow("on top edge")    << QPointF(5, 0)  << true;
+    QTest::newRow("on right edge")  << QPointF(9, 5)  << true;
+    QTest::newRow("on bottom edge") << QPointF(5, 9)  << true;
+    QTest::newRow("inside")         << QPointF(5, 5)  << true;
+    QTest::newRow("outside 1")      << QPointF(-1, 5) << false;
+    QTest::newRow("outside 2")      << QPointF(5, -1) << false;
+    QTest::newRow("outside 3")      << QPointF(10, 5) << false;
+    QTest::newRow("outside 4")      << QPointF(5, 10) << false;
+}
+
+void DecorationButtonTest::testContains()
+{
+    MockBridge bridge;
+    MockDecoration mockDecoration(&bridge);
+
+    MockButton button(KDecoration2::DecorationButtonType::Custom, &mockDecoration);
+    button.setGeometry(QRectF(0, 0, 10, 10));
+    button.setEnabled(true);
+    button.setVisible(true);
+
+    QFETCH(QPointF, pos);
+    QTEST(button.contains(pos), "contains");
+}
+
 QTEST_MAIN(DecorationButtonTest)
 #include "decorationbuttontest.moc"
diff --git a/src/decoration.cpp b/src/decoration.cpp
--- a/src/decoration.cpp
+++ b/src/decoration.cpp
@@ -330,7 +330,7 @@
             continue;
         }
         const bool hovered = button->isHovered();
-        const bool contains = button->geometry().contains(event->pos());
+        const bool contains = button->contains(event->posF());
         if (!hovered && contains) {
             QHoverEvent e(QEvent::HoverEnter, event->posF(), event->oldPosF(), event->modifiers());
             QCoreApplication::instance()->sendEvent(button, &e);
@@ -383,7 +383,7 @@
 void Decoration::wheelEvent(QWheelEvent *event)
 {
     for (DecorationButton *button : d->buttons) {
-        if (button->geometry().contains(event->posF())) {
+        if (button->contains(event->posF())) {
             QCoreApplication::instance()->sendEvent(button, event);
             event->setAccepted(true);
         }
diff --git a/src/decorationbutton.h b/src/decorationbutton.h
--- a/src/decorationbutton.h
+++ b/src/decorationbutton.h
@@ -113,6 +113,11 @@
     bool isCheckable() const;
     DecorationButtonType type() const;
 
+    /**
+     * Returns @c true if @p pos is inside of the button, otherwise returns @c false.
+     **/
+    bool contains(const QPointF &pos) const;
+
     Qt::MouseButtons acceptedButtons() const;
     void setAcceptedButtons(Qt::MouseButtons buttons);
 
diff --git a/src/decorationbutton.cpp b/src/decorationbutton.cpp
--- a/src/decorationbutton.cpp
+++ b/src/decorationbutton.cpp
@@ -445,6 +445,11 @@
 
 #undef DELEGATE
 
+bool DecorationButton::contains(const QPointF &pos) const
+{
+    return d->geometry.toRect().contains(pos.toPoint());
+}
+
 bool DecorationButton::event(QEvent *event)
 {
     switch (event->type()) {
@@ -476,16 +481,16 @@
 
 void DecorationButton::hoverEnterEvent(QHoverEvent *event)
 {
-    if (!d->enabled || !d->visible || !d->geometry.contains(event->posF())) {
+    if (!d->enabled || !d->visible || !contains(event->posF())) {
         return;
     }
     d->setHovered(true);
     event->setAccepted(true);
 }
 
 void DecorationButton::hoverLeaveEvent(QHoverEvent *event)
 {
-    if (!d->enabled || !d->visible || !d->hovered || d->geometry.contains(event->posF())) {
+    if (!d->enabled || !d->visible || !d->hovered || contains(event->posF())) {
         return;
     }
     d->setHovered(false);
@@ -502,15 +507,15 @@
     if (!d->enabled || !d->visible || !d->hovered) {
         return;
     }
-    if (!d->geometry.contains(event->localPos())) {
+    if (!contains(event->localPos())) {
         d->setHovered(false);
         event->setAccepted(true);
     }
 }
 
 void DecorationButton::mousePressEvent(QMouseEvent *event)
 {
-    if (!d->enabled || !d->visible || !d->geometry.contains(event->localPos()) || !d->acceptedButtons.testFlag(event->button())) {
+    if (!d->enabled || !d->visible || !contains(event->localPos()) || !d->acceptedButtons.testFlag(event->button())) {
         return;
     }
     d->setPressed(event->button(), true);
@@ -533,7 +538,7 @@
     if (!d->enabled || !d->visible || !d->isPressed(event->button())) {
         return;
     }
-    if (d->geometry.contains(event->localPos())) {
+    if (contains(event->localPos())) {
         if (!d->pressAndHold || event->button() != Qt::LeftButton) {
             emit clicked(event->button());
         } else {