diff --git a/src/ViewportWidget.cpp b/src/ViewportWidget.cpp
index ec0a9bd..fdade48 100644
--- a/src/ViewportWidget.cpp
+++ b/src/ViewportWidget.cpp
@@ -24,7 +24,7 @@
 #include <QtMath>
 #include <QOpenGLShaderProgram>
 #include <QVector>
-#include <QMap>
+#include <map>
 
 struct PntComparator {
     bool operator()(const gp_Pnt& a, const gp_Pnt& b) const {
@@ -747,7 +747,7 @@ void ViewportWidget::drawSketch(const SketchFeature* sketch)
     glPointSize(5.0f);
 
     QVector<GLfloat> lineVertices;
-    QMap<gp_Pnt, int, PntComparator> vertexCounts;
+    std::map<gp_Pnt, int, PntComparator> vertexCounts;
 
     for (const auto& obj : sketch->objects()) {
         if (obj->type() == SketchObject::ObjectType::Line) {
@@ -763,9 +763,9 @@ void ViewportWidget::drawSketch(const SketchFeature* sketch)
     }
 
     QVector<GLfloat> pointVertices;
-    for (auto it = vertexCounts.constBegin(); it != vertexCounts.constEnd(); ++it) {
-        if (it.value() == 1) {
-            const gp_Pnt& p = it.key();
+    for (const auto& pair : vertexCounts) {
+        if (pair.second == 1) {
+            const gp_Pnt& p = pair.first;
             pointVertices << p.X() << p.Y() << p.Z();
         }
     }