diff --git a/src/libslic3r/Measure.cpp b/src/libslic3r/Measure.cpp
index ef685b15d..b309fc56d 100644
--- a/src/libslic3r/Measure.cpp
+++ b/src/libslic3r/Measure.cpp
@@ -196,14 +196,17 @@ void MeasuringImpl::update_planes()
 
                 if (last_border.size() == 1)
                     m_planes[plane_id].borders.pop_back();
+                else {
+                    assert(m_planes[plane_id].borders.front() == m_planes[plane_id].borders.back());
+                }
             }
         }
-
         continue; // There was no failure.
 
         PLANE_FAILURE:
             m_planes[plane_id].borders.clear();
     }
+    
 }
 
 
@@ -233,15 +236,16 @@ void MeasuringImpl::extract_features()
         for (const std::vector<Vec3d>& border : plane.borders) {
             if (border.size() <= 1)
                 continue;
+            assert(border.front() == border.back());
             int start_idx = -1;
 
             // First calculate angles at all the vertices.
             angles.clear();
             lengths.clear();
-            for (int i=0; i<int(border.size()); ++i) {
-                const Vec3d& v2 = (i == 0 ? border[0] - border[border.size()-1]
-                                        : border[i] - border[i-1]);
-                const Vec3d& v1 = i == (int)border.size()-1 ? border[0] - border.back()
+            for (int i=0; i<int(border.size()); ++i) { // front is the same as back, hence the weird indexing
+                const Vec3d& v2 = (i == 0 ? border[0] - border[border.size()-2]
+                                          : border[i] - border[i-1]);
+                const Vec3d& v1 = i == (int)border.size()-1 ? border[1] - border.back()
                                                     : border[i+1] - border[i];
                 double angle = atan2(-normal.dot(v1.cross(v2)), -v1.dot(v2)) + M_PI;
                 if (angle > M_PI)
@@ -268,10 +272,24 @@ void MeasuringImpl::extract_features()
                     }
                 } else {
                     if (circle) {
-                        // Add the circle and remember indices into borders.
-                        const auto& [center, radius] = get_center_and_radius(border, start_idx, i, trafo);
-                        circles_idxs.emplace_back(start_idx, i);
-                        circles.emplace_back(SurfaceFeature(SurfaceFeatureType::Circle, center, plane.normal, std::nullopt, radius));
+                        // Anything made up of less than 4 points shall not be considered a circle.
+                        if (i-start_idx > 3) {
+                            // This may be just a partial circle, maybe a small one generated by two short edges.
+                            // To qualify as a circle, it should cover at least one quadrant. Check this now.
+                            const auto& [center, radius] = get_center_and_radius(border, start_idx, i, trafo);
+                            const Vec3d& p1 = border[start_idx];
+                            const Vec3d& p2 = border[i];
+                            const Vec3d& p3 = border[size_t(start_idx+i)/2];
+
+                            // Measure angle between the first and the second radiuses. If smaller than 90 deg, measure angle
+                            // between first radius and one corresponding to the middle of the circle.
+                            if ((p1-center).normalized().dot((p2-center).normalized()) < 0.05 // exactly 90 deg might get rejected
+                            || (p1-center).normalized().dot((p3-center).normalized()) < 0.) {
+                                // Add the circle and remember indices into borders.                            
+                                circles_idxs.emplace_back(start_idx, i);
+                                circles.emplace_back(SurfaceFeature(SurfaceFeatureType::Circle, center, plane.normal, std::nullopt, radius));
+                            }
+                        }
                         circle = false;
                     }
                 }