diff -up qtbase-everywhere-src-5.15.4/src/gui/painting/qpaintengineex.cpp.me qtbase-everywhere-src-5.15.4/src/gui/painting/qpaintengineex.cpp
--- qtbase-everywhere-src-5.15.4/src/gui/painting/qpaintengineex.cpp.me	2022-05-30 14:21:52.215469841 +0200
+++ qtbase-everywhere-src-5.15.4/src/gui/painting/qpaintengineex.cpp	2022-05-30 14:22:39.552558748 +0200
@@ -426,7 +426,7 @@ void QPaintEngineEx::stroke(const QVecto
         patternLength *= pw;
         if (qFuzzyIsNull(patternLength)) {
             pen.setStyle(Qt::NoPen);
-        } else if (extent / patternLength > 10000) {
+        } else if (qFuzzyIsNull(extent) || extent / patternLength > 10000) {
             // approximate stream of tiny dashes with semi-transparent solid line
             pen.setStyle(Qt::SolidLine);
             QColor color(pen.color());