diff --git a/doomsday/engine/portable/include/rend_bias.h b/doomsday/engine/portable/include/rend_bias.h
index 2cd4e99dce..1a19da29d1 100644
--- a/doomsday/engine/portable/include/rend_bias.h
+++ b/doomsday/engine/portable/include/rend_bias.h
@@ -48,6 +48,7 @@ typedef struct biastracker_s {
 
 struct vertexillum_s;
 struct rendpoly_s;
+struct biasaffection_s;
 
 extern int      useBias; // Bias lighting enabled.
 extern unsigned int currentTimeSB;