diff --git a/src/mbgl/shader/outline.vertex.glsl b/src/mbgl/shader/outline.vertex.glsl
index 29c16e3de..f720b8d62 100644
--- a/src/mbgl/shader/outline.vertex.glsl
+++ b/src/mbgl/shader/outline.vertex.glsl
@@ -6,5 +6,5 @@ varying vec2 v_pos;
 
 void main() {
     gl_Position = u_matrix * vec4(a_pos, 0, 1);
-    v_pos = (gl_Position.xy + 1.0) / 2.0 * u_world;
+    v_pos = (gl_Position.xy / gl_Position.w + 1.0) / 2.0 * u_world;
 }