diff --git a/src/p_acs.cpp b/src/p_acs.cpp
index aacd5cc4a5..c40ba6b942 100644
--- a/src/p_acs.cpp
+++ b/src/p_acs.cpp
@@ -75,6 +75,7 @@
 #include "actorptrselect.h"
 #include "farchive.h"
 #include "decallib.h"
+#include "p_terrain.h"
 #include "version.h"
 
 #include "g_shared/a_pickups.h"
@@ -4459,6 +4460,7 @@ enum EACSFunctions
 	ACSF_Warp,					// 92
 	ACSF_GetMaxInventory,
 	ACSF_SetSectorDamage,
+	ACSF_SetSectorTerrain,
 	
 	/* Zandronum's - these must be skipped when we reach 99!
 	-100:ResetMap(0),
@@ -5968,6 +5970,18 @@ doplaysound:			if (funcIndex == ACSF_PlayActorSound)
 			}
 			break;
 
+		case ACSF_SetSectorTerrain:
+			if (argCount >= 3)
+			{
+				int terrain = P_FindTerrain(FBehavior::StaticLookupString(args[2]));
+				FSectorTagIterator it(args[0]);
+				int s;
+				while ((s = it.Next()) >= 0)
+				{
+					sectors[s].terrainnum[args[1]] = terrain;
+				}
+			}
+
 		default:
 			break;
 	}