diff --git a/modules/calib3d/src/blobdetector.cpp b/modules/calib3d/src/blobdetector.cpp
index b247cb5683..4fca3fd4b6 100644
--- a/modules/calib3d/src/blobdetector.cpp
+++ b/modules/calib3d/src/blobdetector.cpp
@@ -145,7 +145,7 @@ void BlobDetector::findBlobs(const cv::Mat &image, const cv::Mat &binaryImage, v
     {
       double area = moms.m00;
       double perimeter = arcLength(Mat(contours[contourIdx]), true);
-      double ratio = 4 * M_PI * area / (perimeter * perimeter);
+      double ratio = 4 * CV_PI * area / (perimeter * perimeter);
       if (ratio < params.minCircularity)
         continue;
     }
diff --git a/modules/calib3d/src/circlesgrid.cpp b/modules/calib3d/src/circlesgrid.cpp
index ad4d8bb44b..5f9c0a7e32 100644
--- a/modules/calib3d/src/circlesgrid.cpp
+++ b/modules/calib3d/src/circlesgrid.cpp
@@ -106,7 +106,7 @@ void Graph::floydWarshall(cv::Mat &distanceMatrix, int infinity) const
   for (Vertices::const_iterator it1 = vertices.begin(); it1 != vertices.end(); it1++)
   {
     distanceMatrix.at<int> (it1->first, it1->first) = 0;
-    for (Neighbors::iterator it2 = it1->second.neighbors.begin(); it2 != it1->second.neighbors.end(); it2++)
+    for (Neighbors::const_iterator it2 = it1->second.neighbors.begin(); it2 != it1->second.neighbors.end(); it2++)
     {
       assert( it1->first != *it2 );
       distanceMatrix.at<int> (it1->first, *it2) = edgeWeight;
diff --git a/modules/calib3d/src/circlesgrid.hpp b/modules/calib3d/src/circlesgrid.hpp
index 83a181bf49..bfe415cca1 100644
--- a/modules/calib3d/src/circlesgrid.hpp
+++ b/modules/calib3d/src/circlesgrid.hpp
@@ -100,7 +100,7 @@ struct CirclesGridFinderParameters
   int minGraphConfidence;
   float vertexGain;
   float vertexPenalty;
-  float existingVertexGain;
+  int existingVertexGain;
   float edgeGain;
   float edgePenalty;
   float convexHullFactor;