diff --git a/GraphicsView/include/CGAL/Buffer_for_vao.h b/GraphicsView/include/CGAL/Buffer_for_vao.h
index c70d4a920a2..366ab655767 100644
--- a/GraphicsView/include/CGAL/Buffer_for_vao.h
+++ b/GraphicsView/include/CGAL/Buffer_for_vao.h
@@ -460,9 +460,9 @@ public:
   static void add_point_in_buffer(const KPoint& kp, std::vector<float>& buffer)
   {
     Local_point p=get_local_point(kp);
-    buffer.push_back(p.x());
-    buffer.push_back(p.y());
-    buffer.push_back(p.z());
+    buffer.push_back(static_cast<float>(p.x()));
+    buffer.push_back(static_cast<float>(p.y()));
+    buffer.push_back(static_cast<float>(p.z()));
   }
 
   /// adds `kv` coordinates to `buffer`
@@ -471,9 +471,9 @@ public:
                                    bool inverse_normal=false)
   {
     Local_vector n=(inverse_normal?-get_local_vector(kv):get_local_vector(kv));
-    buffer.push_back(n.x());
-    buffer.push_back(n.y());
-    buffer.push_back(n.z());
+    buffer.push_back(static_cast<float>(n.x()));
+    buffer.push_back(static_cast<float>(n.y()));
+    buffer.push_back(static_cast<float>(n.z()));
   }
 
   ///adds `acolor` RGB components to `buffer`
diff --git a/GraphicsView/include/CGAL/Qt/manipulatedFrame_impl.h b/GraphicsView/include/CGAL/Qt/manipulatedFrame_impl.h
index 617f1df0f7d..96d03db9adc 100644
--- a/GraphicsView/include/CGAL/Qt/manipulatedFrame_impl.h
+++ b/GraphicsView/include/CGAL/Qt/manipulatedFrame_impl.h
@@ -251,7 +251,7 @@ CGAL_INLINE_FUNCTION
 void ManipulatedFrame::computeMouseSpeed(const QMouseEvent *const e) {
   const QPoint delta = (e->pos() - prevPos_);
   const qreal dist = sqrt(qreal(delta.x() * delta.x() + delta.y() * delta.y()));
-  delay_ = last_move_time.restart();
+  delay_ = static_cast<int>(last_move_time.restart());
   if (delay_ == 0)
     // Less than a millisecond: assume delay = 1ms
     mouseSpeed_ = dist;
diff --git a/GraphicsView/include/CGAL/Qt/qglviewer_impl.h b/GraphicsView/include/CGAL/Qt/qglviewer_impl.h
index 8b2cad8f9a1..0dc7256cb38 100644
--- a/GraphicsView/include/CGAL/Qt/qglviewer_impl.h
+++ b/GraphicsView/include/CGAL/Qt/qglviewer_impl.h
@@ -2248,7 +2248,7 @@ void CGAL::QGLViewer::keyPressEvent(QKeyEvent *e) {
     static QElapsedTimer doublePress;
 
     if (modifiers == playPathKeyboardModifiers()) {
-      int elapsed = doublePress.restart();
+      qint64 elapsed = doublePress.restart();
       if ((elapsed < 250) && (index == previousPathId_))
         camera()->resetPath(index);
       else {
@@ -2263,7 +2263,7 @@ void CGAL::QGLViewer::keyPressEvent(QKeyEvent *e) {
       }
       previousPathId_ = index;
     } else if (modifiers == addKeyFrameKeyboardModifiers()) {
-      int elapsed = doublePress.restart();
+      qint64 elapsed = doublePress.restart();
       if ((elapsed < 250) && (index == previousPathId_)) {
         if (camera()->keyFrameInterpolator(index)) {
           disconnect(camera()->keyFrameInterpolator(index),
diff --git a/Polyhedron/demo/Polyhedron/Color_map.h b/Polyhedron/demo/Polyhedron/Color_map.h
index 46164c649cb..2e04a3ee5bd 100644
--- a/Polyhedron/demo/Polyhedron/Color_map.h
+++ b/Polyhedron/demo/Polyhedron/Color_map.h
@@ -8,7 +8,7 @@ inline QColor generate_color(double h, double s_min = 0.35)
   std::size_t s_max=255;
   if(h >0.8 && h < 0.95) //span of ugly pink, desaturates make it less garish IMO
     s_max = 160;
-  std::size_t s = std::rand() % (s_max-static_cast<std::size_t>(s_min*255)) +s_min*255;
+  std::size_t s = std::rand() % (s_max-static_cast<std::size_t>(s_min*255)) + static_cast<int>(s_min*255);
   return QColor::fromHsvF(h,s/255.0,1.0);
 }
 
diff --git a/Polyhedron/demo/Polyhedron/Plugins/Mesh_3/C3t3_rib_exporter_plugin.cpp b/Polyhedron/demo/Polyhedron/Plugins/Mesh_3/C3t3_rib_exporter_plugin.cpp
index 89b8a92ecc3..edf8e6b13f7 100644
--- a/Polyhedron/demo/Polyhedron/Plugins/Mesh_3/C3t3_rib_exporter_plugin.cpp
+++ b/Polyhedron/demo/Polyhedron/Plugins/Mesh_3/C3t3_rib_exporter_plugin.cpp
@@ -755,8 +755,8 @@ write_surface_cells(const C3t3& c3t3, const Plane& /* plane */, std::ofstream& o
       
     //const int TRANSPARENCY_ALPHA_VALUE = 100;
     CGAL::Bbox_3 bbox = c3t3.bbox();
-    float relPos = (c->weighted_circumcenter().x() - bbox.xmin()) 
-                   / (bbox.xmax() - bbox.xmin());
+    float relPos = static_cast<float>((c->weighted_circumcenter().x() - bbox.xmin()) 
+                                      / (bbox.xmax() - bbox.xmin()));
     float TRANSPARENCY_ALPHA_VALUE = 
       1.f - 
       (relPos < 0.25f ? 
@@ -842,7 +842,7 @@ write_surface_cells(const C3t3& c3t3, const Plane& /* plane */, std::ofstream& o
       {
         if (i == last_2D_vertex_index)
         {
-          edgecolor.setAlpha(TRANSPARENCY_ALPHA_VALUE);
+          edgecolor.setAlphaF(TRANSPARENCY_ALPHA_VALUE);
         }
         else
         {
diff --git a/Polyhedron/demo/Polyhedron/Plugins/PCA/Basic_generator_plugin.cpp b/Polyhedron/demo/Polyhedron/Plugins/PCA/Basic_generator_plugin.cpp
index 269eb121ae4..abc04bc2849 100644
--- a/Polyhedron/demo/Polyhedron/Plugins/PCA/Basic_generator_plugin.cpp
+++ b/Polyhedron/demo/Polyhedron/Plugins/PCA/Basic_generator_plugin.cpp
@@ -777,7 +777,8 @@ void Basic_generator_plugin::generateGrid()
 
   QString points_text;
   Point extrema[2];
-  typename boost::graph_traits<Face_graph>::vertices_size_type nb_cells[2];
+  using size_type = typename boost::graph_traits<Face_graph>::vertices_size_type;
+  size_type nb_cells[2];
   bool triangulated = dock_widget->grid_checkBox->isChecked();
   points_text= dock_widget->grid_lineEdit->text();
 
@@ -806,8 +807,8 @@ void Basic_generator_plugin::generateGrid()
   }
   extrema[0] = Point(coords[0], coords[1], coords[2]);
   extrema[1] = Point(coords[3], coords[4], coords[5]);
-  nb_cells[0] = static_cast<std::size_t>(dock_widget->gridX_spinBox->value());
-  nb_cells[1] = static_cast<std::size_t>(dock_widget->gridY_spinBox->value());
+  nb_cells[0] = static_cast<size_type>(dock_widget->gridX_spinBox->value());
+  nb_cells[1] = static_cast<size_type>(dock_widget->gridY_spinBox->value());
 
   //nb_points = nb_cells+1
   Point_generator point_gen(nb_cells[0]+1, nb_cells[1]+1, extrema[0], extrema[1]);