diff --git a/lib/jkqtplotter/graphs/jkqtpscatter.cpp b/lib/jkqtplotter/graphs/jkqtpscatter.cpp
index cba15c5ad8..06446c3b94 100644
--- a/lib/jkqtplotter/graphs/jkqtpscatter.cpp
+++ b/lib/jkqtplotter/graphs/jkqtpscatter.cpp
@@ -128,7 +128,7 @@ void JKQTPXYLineGraph::draw(JKQTPEnhancedPainter& painter) {
                 //qDebug()<<"JKQTPXYLineGraph::draw(): linesToDraw.size()=="<<linesToDraw.size()<<", clip: x="<<xmin<<".."<<xmax<<", y="<<ymin<<".."<<ymax;
                 for (const auto &linesPFromV : linesToDraw) {
                     //qDebug()<<"JKQTPXYLineGraph::draw():   linesPFromV.size()=="<<linesPFromV.size()<<"   useNonvisibleLineCompression="<<getUseNonvisibleLineCompression();
-                    const QList<QPointF> linesP=getUseNonvisibleLineCompression()?JKQTPSimplifyPolyLines(linesPFromV, p.widthF()*getNonvisibleLineCompressionAgressiveness()):linesPFromV;
+                    const QPolygonF linesP=getUseNonvisibleLineCompression()?JKQTPSimplifyPolyLines(linesPFromV, p.widthF()*getNonvisibleLineCompressionAgressiveness()):linesPFromV;
                     //qDebug()<<"JKQTPXYLineGraph::draw():     --> linesP.size()=="<<linesP.size();
                     if (linesP.size()>0) {
                         if (isHighlighted()) {
diff --git a/lib/jkqtplotter/graphs/jkqtpspecialline.cpp b/lib/jkqtplotter/graphs/jkqtpspecialline.cpp
index 680a45fa4e..52777f0c2b 100644
--- a/lib/jkqtplotter/graphs/jkqtpspecialline.cpp
+++ b/lib/jkqtplotter/graphs/jkqtpspecialline.cpp
@@ -274,7 +274,7 @@ void JKQTPSpecialLineHorizontalGraph::draw(JKQTPEnhancedPainter& painter) {
         if (isHighlighted()) {
             painter.setBrush(Qt::NoBrush);
             painter.setPen(ph);
-            for (const auto &lines : pl_fordrawing) {
+            for (const QPolygonF lines : pl_fordrawing) {
                 painter.drawPolyline(lines);
             }
         }
@@ -282,7 +282,7 @@ void JKQTPSpecialLineHorizontalGraph::draw(JKQTPEnhancedPainter& painter) {
         if (getDrawLine()) {
             painter.setBrush(Qt::NoBrush);
             painter.setPen(p);
-            for (const auto &lines : pl_fordrawing) {
+            for (const QPolygonF lines : pl_fordrawing) {
                 painter.drawPolyline(lines);
             }
         }
@@ -460,7 +460,7 @@ void JKQTPSpecialLineVerticalGraph::draw(JKQTPEnhancedPainter& painter) {
         if (isHighlighted()) {
             painter.setBrush(Qt::NoBrush);
             painter.setPen(ph);
-            for (const auto &lines : pl_fordrawing) {
+            for (const QPolygonF lines : pl_fordrawing) {
                 painter.drawPolyline(lines);
             }
         }
@@ -468,7 +468,7 @@ void JKQTPSpecialLineVerticalGraph::draw(JKQTPEnhancedPainter& painter) {
         if (getDrawLine()) {
             painter.setBrush(Qt::NoBrush);
             painter.setPen(p);
-            for (const auto &lines : pl_fordrawing) {
+            for (const QPolygonF lines : pl_fordrawing) {
                 painter.drawPolyline(lines);
             }
         }