diff --git a/src/gui/painting/qpaintengineex.cpp b/src/gui/painting/qpaintengineex.cpp
index d752c01f6a..2997d53310 100644
--- a/src/gui/painting/qpaintengineex.cpp
+++ b/src/gui/painting/qpaintengineex.cpp
@@ -938,6 +938,7 @@ void QPaintEngineEx::drawPoints(const QPoint *points, int pointCount)
 
 void QPaintEngineEx::drawPolygon(const QPointF *points, int pointCount, PolygonDrawMode mode)
 {
+    Q_ASSUME(pointCount >= 2);
     QVectorPath path((const qreal *) points, pointCount, nullptr, QVectorPath::polygonFlags(mode));
 
     if (mode == PolylineMode)
@@ -948,6 +949,7 @@ void QPaintEngineEx::drawPolygon(const QPointF *points, int pointCount, PolygonD
 
 void QPaintEngineEx::drawPolygon(const QPoint *points, int pointCount, PolygonDrawMode mode)
 {
+    Q_ASSUME(pointCount >= 2);
     int count = pointCount<<1;
     QVarLengthArray<qreal> pts(count);