diff --git a/src/actor.h b/src/actor.h
index 74516301af..d9d1dbcfe4 100644
--- a/src/actor.h
+++ b/src/actor.h
@@ -329,6 +329,7 @@ enum
 	MF6_SEEINVISIBLE	= 0x01000000,	// Monsters can see invisible player.
 	MF6_DONTCORPSE		= 0x02000000,	// [RC] Don't autoset MF_CORPSE upon death and don't force Crash state change.
 	MF6_POISONALWAYS	= 0x04000000,	// Always apply poison, even when target can't take the damage.
+	MF6_DOHARMSPECIES	= 0x08000000,	// Do hurt one's own species with projectiles.
 
 // --- mobj.renderflags ---
 
diff --git a/src/p_map.cpp b/src/p_map.cpp
index 73b17e7d15..943852526f 100644
--- a/src/p_map.cpp
+++ b/src/p_map.cpp
@@ -1074,7 +1074,7 @@ bool PIT_CheckThing (AActor *thing, FCheckPosition &tm)
 						// [RH] Don't hurt monsters that hate the same thing as you do
 						return false;
 					}
-					if (thing->GetSpecies() == tm.thing->target->GetSpecies())
+					if (thing->GetSpecies() == tm.thing->target->GetSpecies() && !(thing->flags6 & MF6_DOHARMSPECIES))
 					{
 						// Don't hurt same species or any relative -
 						// but only if the target isn't one's hostile.
diff --git a/src/thingdef/thingdef_data.cpp b/src/thingdef/thingdef_data.cpp
index 24b0200f90..f82b453741 100644
--- a/src/thingdef/thingdef_data.cpp
+++ b/src/thingdef/thingdef_data.cpp
@@ -231,6 +231,7 @@ static FFlagDef ActorFlags[]=
 	DEFINE_FLAG(MF6, NOMENU, AActor, flags6),
 	DEFINE_FLAG(MF6, SEEINVISIBLE, AActor, flags6),
 	DEFINE_FLAG(MF6, DONTCORPSE, AActor, flags6),
+	DEFINE_FLAG(MF6, DOHARMSPECIES, AActor, flags6),
 	DEFINE_FLAG(MF6, POISONALWAYS, AActor, flags6),
 
 	// Effect flags