diff --git a/src/slic3r/GUI/Gizmos/GLGizmoFlatten.cpp b/src/slic3r/GUI/Gizmos/GLGizmoFlatten.cpp
index 9c65f18eb..4ad8136bb 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmoFlatten.cpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmoFlatten.cpp
@@ -141,6 +141,7 @@ void GLGizmoFlatten::update_planes()
     // Following constants are used for discarding too small polygons.
     const float minimal_area = 5.f; // in square mm (world coordinates)
     const float minimal_side = 1.f; // mm
+    const float minimal_angle = 1.f; // degree, initial value was 10, but cause bugs
 
     // Now we'll go through all the facets and append Points of facets sharing the same normal.
     // This part is still performed in mesh coordinate system.
@@ -235,7 +236,7 @@ void GLGizmoFlatten::update_planes()
             discard = true;
         else {
             // We also check the inner angles and discard polygons with angles smaller than the following threshold
-            const double angle_threshold = ::cos(10.0 * (double)PI / 180.0);
+            const double angle_threshold = ::cos(minimal_angle * (double)PI / 180.0);
 
             for (unsigned int i = 0; i < polygon.size(); ++i) {
                 const Vec3d& prec = polygon[(i == 0) ? polygon.size() - 1 : i - 1];