diff --git a/examples/37-gpudrivenrendering/varying.def.sc b/examples/37-gpudrivenrendering/varying.def.sc
index f0615767d..bab2e384d 100644
--- a/examples/37-gpudrivenrendering/varying.def.sc
+++ b/examples/37-gpudrivenrendering/varying.def.sc
@@ -6,4 +6,4 @@ vec4 i_data2     : TEXCOORD5;
 vec4 i_data3     : TEXCOORD4;
 
 vec2  v_texcoord0 : TEXCOORD0;
-float v_materialID : TEXCOORD0;
+flat float v_materialID : TEXCOORD0;