diff --git a/3d-viewer/3d_cache/sg/sg_shape.cpp b/3d-viewer/3d_cache/sg/sg_shape.cpp
index 447b59bc82..f5543e792e 100644
--- a/3d-viewer/3d_cache/sg/sg_shape.cpp
+++ b/3d-viewer/3d_cache/sg/sg_shape.cpp
@@ -752,7 +752,9 @@ bool SGSHAPE::Prepare( const glm::dmat4* aTransform, S3D::MATLIST& materials,
     for( unsigned int i = 0; i < nvidx; ++i )
     {
         mit = indexmap.find( lv[i] );
-        lvidx[i] = mit->second;
+
+        if( mit != indexmap.end() )
+            lvidx[i] = mit->second;
     }
 
     m.m_FaceIdxSize = (unsigned int )nvidx;
diff --git a/3d-viewer/3d_canvas/create_layer_items.cpp b/3d-viewer/3d_canvas/create_layer_items.cpp
index 2ed71ff2a8..5b3222a6d6 100644
--- a/3d-viewer/3d_canvas/create_layer_items.cpp
+++ b/3d-viewer/3d_canvas/create_layer_items.cpp
@@ -797,8 +797,11 @@ void BOARD_ADAPTER::createLayers( REPORTER* aStatusReporter )
                     {
                         auto mut_it = layer_lock.find( layer );
 
-                        std::lock_guard< std::mutex > lock( *( mut_it->second ) );
-                        zone->TransformSolidAreasShapesToPolygon( layer, *m_layers_poly[layer] );
+                        if( mut_it != layer_lock.end() )
+                        {
+                            std::lock_guard< std::mutex > lock( *( mut_it->second ) );
+                            zone->TransformSolidAreasShapesToPolygon( layer, *m_layers_poly[layer] );
+                        }
                     }
                 }