diff --git a/src/p_local.h b/src/p_local.h
index 5f47f8d05946c13262e5711f2f161e7c06d518b7..2f56602559a439400d2ea960ec22a92352be62f6 100644
--- a/src/p_local.h
+++ b/src/p_local.h
@@ -308,7 +308,7 @@ void P_PushableThinker(mobj_t *mobj);
 void P_SceneryThinker(mobj_t *mobj);
 
 fixed_t P_MobjFloorZ(sector_t *sector, sector_t *boundsec, fixed_t x, fixed_t y, fixed_t radius, line_t *line, boolean lowest, boolean perfect);
-fixed_t P_MobjCeilingZ(sector_t *sector, sector_t *boundsec, fixed_t x, fixed_t y, fixed_t radius, line_t *line, boolean lowest, boolean perfect);
+fixed_t P_MobjCeilingZ(sector_t *sector, sector_t *boundsec, fixed_t x, fixed_t y, fixed_t radius, line_t *line, boolean highest, boolean perfect);
 #define P_GetFloorZ(mobj, sector, x, y, line) P_MobjFloorZ(sector, NULL, x, y, mobj->radius, line, false, false)
 #define P_GetCeilingZ(mobj, sector, x, y, line) P_MobjCeilingZ(sector, NULL, x, y, mobj->radius, line, true, false)
 #define P_GetFOFTopZ(mobj, sector, fof, x, y, line) P_MobjCeilingZ(sectors + fof->secnum, sector, x, y, mobj->radius, line, false, false)