diff --git a/common/d_iface.h b/common/d_iface.h
index db74ad2..a558d06 100644
--- a/common/d_iface.h
+++ b/common/d_iface.h
@@ -218,6 +218,7 @@ void R_DrawSurface (void);
 // !!! if this is changed, it must be changed in d_ifacea.h too !!!
 #define	CYCLE			128		// turbulent cycle size
 
+#define TILE_SIZE		128		// size of textures generated by R_GenTiledSurf
 
 #define SKYSHIFT		7
 #define	SKYSIZE			(1 << SKYSHIFT)