diff --git a/src/p_floor.c b/src/p_floor.c
index 5ee08beea..921d11b6c 100644
--- a/src/p_floor.c
+++ b/src/p_floor.c
@@ -15,7 +15,9 @@
 #include "doomstat.h"
 #include "m_random.h"
 #include "p_local.h"
+#ifdef ESLOPE
 #include "p_slopes.h"
+#endif
 #include "r_state.h"
 #include "s_sound.h"
 #include "z_zone.h"
@@ -2968,10 +2970,12 @@ void EV_CrumbleChain(sector_t *sec, ffloor_t *rover)
 			if (R_PointInSubsector(a, b)->sector == sec)
 			{
 				mobj_t *spawned = NULL;
+#ifdef ESLOPE
 				if (*rover->t_slope)
 					topz = P_GetZAt(*rover->t_slope, a, b) - (spacing>>1);
 				if (*rover->b_slope)
 					bottomz = P_GetZAt(*rover->b_slope, a, b);
+#endif
 
 				for (c = topz; c > bottomz; c -= spacing)
 				{