diff --git a/src/core/qgssggeometry.cpp b/src/core/qgssggeometry.cpp
index 3fec7e8ac8..19f1097c3f 100644
--- a/src/core/qgssggeometry.cpp
+++ b/src/core/qgssggeometry.cpp
@@ -164,7 +164,7 @@ QSGGeometry *QgsSGGeometry::qgsPolygonToQSGGeometry( const QgsPolygon *polygon,
   Q_ASSERT( polygon );
 
   QgsGeometry geom( polygon->clone() );
-  geom = geom.buffer( 0.0000001, 5 );
+  geom = geom.buffer( 0.0000001, 1, Qgis::EndCapStyle::Flat, Qgis::JoinStyle::Miter, 5 );
   QgsPolygon *bufferedPolygon = qgsgeometry_cast<QgsPolygon *>( geom.constGet() );
   QgsTessellator t( visibleExtent.xMinimum(), visibleExtent.yMaximum(), false, false, false, true );
   if ( bufferedPolygon )
diff --git a/src/core/sgrubberband.cpp b/src/core/sgrubberband.cpp
index 64e30ab2d5..d1b23b54a5 100644
--- a/src/core/sgrubberband.cpp
+++ b/src/core/sgrubberband.cpp
@@ -109,7 +109,9 @@ QSGGeometryNode *SGRubberband::createLineGeometry( const QVector<QgsPoint> &poin
 QSGGeometryNode *SGRubberband::createPolygonGeometry( const QVector<QgsPoint> &points )
 {
   QgsGeometry geom( new QgsPolygon( new QgsLineString( points ) ) );
-  geom = geom.buffer( 0.0000001, 5 );
+  geom = geom.buffer( 0.0000001, 1, Qgis::EndCapStyle::Flat, Qgis::JoinStyle::Miter, 5 );
+  // QgsTesselator doesn't allow for coordinates distance smaller than 0.001
+  geom.removeDuplicateNodes( 0.001 );
   QgsPolygon *polygon = qgsgeometry_cast<QgsPolygon *>( geom.constGet() );
   QgsTessellator t( 0, 0, false, false, false, true );
   if ( points.size() > 2 && polygon )