diff --git a/plugins/SimulationView/layers3d.shader b/plugins/SimulationView/layers3d.shader
index 2633b54787..14a766f764 100644
--- a/plugins/SimulationView/layers3d.shader
+++ b/plugins/SimulationView/layers3d.shader
@@ -192,6 +192,7 @@ geometry41core =
         } else {
             // All normal lines are rendered as 3d tubes.
             myEmitVertex(v_vertex[0], v_color[0], g_vertex_normal_horz, u_viewProjectionMatrix * (gl_in[0].gl_Position + g_vertex_offset_horz));
+            myEmitVertex(v_vertex[0], v_color[0], g_vertex_normal_horz, u_viewProjectionMatrix * (gl_in[0].gl_Position + g_vertex_offset_horz));
             myEmitVertex(v_vertex[1], v_color[1], g_vertex_normal_horz, u_viewProjectionMatrix * (gl_in[1].gl_Position + g_vertex_offset_horz));
             myEmitVertex(v_vertex[0], v_color[0], g_vertex_normal_vert, u_viewProjectionMatrix * (gl_in[0].gl_Position + g_vertex_offset_vert));
             myEmitVertex(v_vertex[1], v_color[1], g_vertex_normal_vert, u_viewProjectionMatrix * (gl_in[1].gl_Position + g_vertex_offset_vert));