diff --git a/src/slic3r/GUI/3DScene.cpp b/src/slic3r/GUI/3DScene.cpp
index cb7ff02fd2..2e0d224fde 100644
--- a/src/slic3r/GUI/3DScene.cpp
+++ b/src/slic3r/GUI/3DScene.cpp
@@ -1162,13 +1162,14 @@ void GLVolumeCollection::update_colors_by_extruder(const DynamicPrintConfig *con
 
         const ColorItem& color = colors[extruder_id];
         if (!color.first.empty()) {
-			if (!is_update_alpha) {
-                float old_a   = color.second.a();
+            if (!is_update_alpha) {
+                float old_a   = volume->color.a();
                 volume->color = color.second;
                 volume->color.a(old_a);
-			}
-            volume->color = color.second;
-		}
+            } else {
+                volume->color = color.second;
+            }
+        }
     }
 }
 
diff --git a/src/slic3r/GUI/GCodeViewer.cpp b/src/slic3r/GUI/GCodeViewer.cpp
index e703a4051d..1e607bd5f1 100644
--- a/src/slic3r/GUI/GCodeViewer.cpp
+++ b/src/slic3r/GUI/GCodeViewer.cpp
@@ -1242,11 +1242,12 @@ void GCodeViewer::render(int canvas_width, int canvas_height, int right_margin)
     m_statistics.total_instances_gpu_size = 0;
 #endif // ENABLE_GCODE_VIEWER_STATISTICS
 
+    glsafe(::glEnable(GL_DEPTH_TEST));
+    render_shells();
+
     if (m_roles.empty())
         return;
 
-    glsafe(::glEnable(GL_DEPTH_TEST));
-    render_shells();
     render_toolpaths();
     float legend_height = 0.0f;
     render_legend(legend_height, canvas_width, canvas_height, right_margin);