diff --git a/src/widget/wknobcomposed.cpp b/src/widget/wknobcomposed.cpp
index e1f52970f79c..d683689c6132 100644
--- a/src/widget/wknobcomposed.cpp
+++ b/src/widget/wknobcomposed.cpp
@@ -195,11 +195,11 @@ void WKnobComposed::drawArc(QPainter* pPainter) {
     arcPen.setCapStyle(m_arcPenCap);
 
     pPainter->setPen(arcPen);
-    if (m_defaultAngle) {
+    if (m_defaultAngle.has_value()) {
         // draw arc from default angle to current angle
         pPainter->drawArc(m_rect,
-                static_cast<int>((90 - m_defaultAngle.value()) * 16),
-                static_cast<int>((m_dCurrentAngle - m_defaultAngle.value()) * -16));
+                static_cast<int>((90 - *m_defaultAngle) * 16),
+                static_cast<int>((m_dCurrentAngle - *m_defaultAngle) * -16));
     } else if (m_arcUnipolar) {
         if (m_arcReversed) {
            // draw arc from maxAngle to current position