diff --git a/Classification/include/CGAL/Classification/Random_forest_classifier.h b/Classification/include/CGAL/Classification/Random_forest_classifier.h
index 7aaf44c4ed7..10844a3496e 100644
--- a/Classification/include/CGAL/Classification/Random_forest_classifier.h
+++ b/Classification/include/CGAL/Classification/Random_forest_classifier.h
@@ -127,15 +127,15 @@ public:
       if (ground_truth[i] != -1)
         ++ nb_samples;
 
-    cv::Mat training_features (nb_samples, m_features.size(), CV_32FC1);
-    cv::Mat training_labels (nb_samples, 1, CV_32FC1);
+    cv::Mat training_features (int(nb_samples), int(m_features.size()), CV_32FC1);
+    cv::Mat training_labels (int(nb_samples), 1, CV_32FC1);
 
     for (std::size_t i = 0, index = 0; i < ground_truth.size(); ++ i)
       if (ground_truth[i] != -1)
       {
         for (std::size_t f = 0; f < m_features.size(); ++ f)
-          training_features.at<float>(index, f) = m_features[f]->value(i);
-        training_labels.at<float>(index, 0) = ground_truth[i];
+          training_features.at<float>(int(index), int(f)) = m_features[f]->value(i);
+        training_labels.at<float>(int(index), 0) = ground_truth[i];
         ++ index;
       }
 
@@ -194,9 +194,9 @@ public:
   {
     out.resize (m_labels.size(), 0.);
     
-    cv::Mat feature (1, m_features.size(), CV_32FC1);
+    cv::Mat feature (1, int(m_features.size()), CV_32FC1);
     for (std::size_t f = 0; f < m_features.size(); ++ f)
-      feature.at<float>(0, f) = m_features[f]->value(item_index);
+      feature.at<float>(0, int(f)) = m_features[f]->value(item_index);
 
 //compute the result of each tree
 #if (CV_MAJOR_VERSION < 3)