diff --git a/src/modules/fiberDisplaySimple/shaders/WMFiberDisplaySimple-vertex.glsl b/src/modules/fiberDisplaySimple/shaders/WMFiberDisplaySimple-vertex.glsl
index f21cf1879ad15df9b1d89ab5e5037343cab4ce9c..23178e2e8293429dc5eb46b46e9a882f43e2f196 100644
--- a/src/modules/fiberDisplaySimple/shaders/WMFiberDisplaySimple-vertex.glsl
+++ b/src/modules/fiberDisplaySimple/shaders/WMFiberDisplaySimple-vertex.glsl
@@ -73,7 +73,9 @@ void main()
 
     // The same accounds for the vertex. Transfer it to world-space.
     v_vertex = gl_ModelViewMatrix * gl_Vertex;
-    v_normal
+
+    // fill this varying with a dummy. Not always needed.
+    v_normal = vec3( 1.0, 0.0, 0.0 );
 
     // Grab the tangent. We have uploaded it normalized in gl_Normal per vertex
     // We need to transfer it to the world-space ass all further operations are done there.