diff --git a/src/r_plane.h b/src/r_plane.h
index 64b339d04..8730bcefd 100644
--- a/src/r_plane.h
+++ b/src/r_plane.h
@@ -73,7 +73,6 @@ extern visplane_t *ceilingplane;
 // Visplane related.
 extern INT16 *lastopening, *openings;
 extern size_t maxopenings;
-typedef void (*planefunction_t)(INT32 top, INT32 bottom);
 
 extern INT16 floorclip[MAXVIDWIDTH], ceilingclip[MAXVIDWIDTH];
 extern fixed_t frontscale[MAXVIDWIDTH], yslopetab[MAXVIDHEIGHT*4];