diff --git a/src/mol-gl/shader/chunks/assign-material-color.glsl.ts b/src/mol-gl/shader/chunks/assign-material-color.glsl.ts
index c147051ec483c6b642b3d0a3af4c4ad224b9634d..9d550b8f14277d2fd128601971edcc78cf9d9136 100644
--- a/src/mol-gl/shader/chunks/assign-material-color.glsl.ts
+++ b/src/mol-gl/shader/chunks/assign-material-color.glsl.ts
@@ -3,9 +3,8 @@ export const assign_material_color = `
     #if defined(dMarkerType_uniform)
         float marker = uMarker;
     #elif defined(dMarkerType_groupInstance)
-        float marker = vMarker;
+        float marker = floor(vMarker * 255.0 + 0.5); // rounding required to work on some cards on win
     #endif
-    marker = floor(marker * 255.0 + 0.5); // rounding required to work on some cards on win
 #endif
 
 #if defined(dRenderVariant_color)