diff --git a/src/actor.h b/src/actor.h
index dac14a8229..b1a46892e0 100644
--- a/src/actor.h
+++ b/src/actor.h
@@ -1271,6 +1271,7 @@ public:
 	void UnlinkFromWorld(FLinkContext *ctx);
 	void AdjustFloorClip ();
 	bool InStateSequence(FState * newstate, FState * basestate);
+	bool IsMapActor();
 	int GetTics(FState * newstate);
 	bool SetState (FState *newstate, bool nofunction=false);
 	virtual void SplashCheck();
diff --git a/src/c_cmds.cpp b/src/c_cmds.cpp
index 18be473e80..57c4c20ea6 100644
--- a/src/c_cmds.cpp
+++ b/src/c_cmds.cpp
@@ -914,10 +914,7 @@ static bool IsActorACountItem(AActor *mo)
 // [SP] for all actors
 static bool IsActor(AActor *mo)
 {
-	if (mo->IsKindOf(RUNTIME_CLASS(AInventory)))
-		return static_cast<AInventory *>(mo)->Owner == NULL; // [SP] Exclude inventory-owned items
-	else
-		return true;
+	return mo->IsMapActor();
 }
 
 // [SP] modified - now allows showing count only, new arg must be passed. Also now still counts regardless, if lists are printed.
diff --git a/src/d_net.cpp b/src/d_net.cpp
index 609311cb42..583b99ebf0 100644
--- a/src/d_net.cpp
+++ b/src/d_net.cpp
@@ -2100,7 +2100,7 @@ static int RemoveClass(const PClass *cls)
 				continue;
 			}
 			// [SP] Don't remove owned inventory objects.
-			if (actor->IsKindOf(RUNTIME_CLASS(AInventory)) && static_cast<AInventory *>(actor)->Owner != NULL)
+			if (!actor->IsMapActor())
 			{
 				continue;
 			}
diff --git a/src/fragglescript/t_func.cpp b/src/fragglescript/t_func.cpp
index abfec10334..13f42b4fe5 100644
--- a/src/fragglescript/t_func.cpp
+++ b/src/fragglescript/t_func.cpp
@@ -3134,16 +3134,7 @@ void FParser::SF_MapThingNumExist()
 		}
 		else
 		{
-			// Inventory items in the player's inventory have to be considered non-present.
-			if (SpawnedThings[intval]->IsKindOf(RUNTIME_CLASS(AInventory)) && 
-				barrier_cast<AInventory*>(SpawnedThings[intval])->Owner != NULL)
-			{
-				t_return.value.i = 0;
-			}
-			else
-			{
-				t_return.value.i = 1;
-			}
+			t_return.value.i = SpawnedThings[intval]->IsMapActor();
 			t_return.type = svt_int;
 		}
 	}
@@ -3673,8 +3664,7 @@ again:
 			{
 				if (mo->IsA(pClass))
 				{
-					if (!mo->IsKindOf (RUNTIME_CLASS(AInventory)) ||
-						static_cast<AInventory *>(mo)->Owner == NULL)
+					if (mo->IsMapActor())
 					{
 						count++;
 					}
diff --git a/src/fragglescript/t_variable.cpp b/src/fragglescript/t_variable.cpp
index 47735d26f0..6ece4f22ab 100644
--- a/src/fragglescript/t_variable.cpp
+++ b/src/fragglescript/t_variable.cpp
@@ -129,9 +129,7 @@ AActor* actorvalue(const svalue_t &svalue)
 	if(svalue.type == svt_mobj) 
 	{
 		// Inventory items in the player's inventory have to be considered non-present.
-		if (svalue.value.mobj != NULL && 
-			svalue.value.mobj->IsKindOf(RUNTIME_CLASS(AInventory)) && 
-			static_cast<AInventory*>(svalue.value.mobj)->Owner != NULL)
+		if (svalue.value.mobj == NULL || !svalue.value.mobj->IsMapActor())
 		{
 			return NULL;
 		}
@@ -150,9 +148,7 @@ AActor* actorvalue(const svalue_t &svalue)
 			return NULL;
 		}
 		// Inventory items in the player's inventory have to be considered non-present.
-		if (SpawnedThings[intval] != NULL &&
-			SpawnedThings[intval]->IsKindOf(RUNTIME_CLASS(AInventory)) && 
-			barrier_cast<AInventory*>(SpawnedThings[intval])->Owner != NULL)
+		if (svalue.value.mobj == NULL || !svalue.value.mobj->IsMapActor())
 		{
 			return NULL;
 		}
diff --git a/src/p_acs.cpp b/src/p_acs.cpp
index 52786b2f94..287db7cde8 100644
--- a/src/p_acs.cpp
+++ b/src/p_acs.cpp
@@ -3697,8 +3697,7 @@ do_count:
 				if (tag == -1 || tagManager.SectorHasTag(actor->Sector, tag))
 				{
 					// Don't count items in somebody's inventory
-					if (!actor->IsKindOf (RUNTIME_CLASS(AInventory)) ||
-						static_cast<AInventory *>(actor)->Owner == NULL)
+					if (actor->IsMapActor())
 					{
 						count++;
 					}
@@ -3717,8 +3716,7 @@ do_count:
 				if (tag == -1 || tagManager.SectorHasTag(actor->Sector, tag))
 				{
 					// Don't count items in somebody's inventory
-					if (!actor->IsKindOf (RUNTIME_CLASS(AInventory)) ||
-						static_cast<AInventory *>(actor)->Owner == NULL)
+					if (actor->IsMapActor())
 					{
 						count++;
 					}
diff --git a/src/p_mobj.cpp b/src/p_mobj.cpp
index 804397a05f..6699354052 100644
--- a/src/p_mobj.cpp
+++ b/src/p_mobj.cpp
@@ -620,6 +620,14 @@ DEFINE_ACTION_FUNCTION(AActor, InStateSequence)
 	PARAM_POINTER(basestate, FState);
 	ACTION_RETURN_BOOL(self->InStateSequence(newstate, basestate));
 }
+
+
+bool AActor::IsMapActor()
+{
+	// [SP] Don't remove owned inventory objects.
+	return (!IsKindOf(RUNTIME_CLASS(AInventory)) || static_cast<AInventory *>(this)->Owner == nullptr);
+}
+
 //==========================================================================
 //
 // AActor::GetTics
diff --git a/src/p_things.cpp b/src/p_things.cpp
index 8b38141d71..4cac8866f4 100644
--- a/src/p_things.cpp
+++ b/src/p_things.cpp
@@ -423,7 +423,7 @@ void P_RemoveThing(AActor * actor)
 	if (actor->player == NULL || actor != actor->player->mo)
 	{
 		// Don't also remove owned inventory items
-		if (actor->IsKindOf(RUNTIME_CLASS(AInventory)) && static_cast<AInventory*>(actor)->Owner != NULL) return;
+		if (!actor->IsMapActor())
 
 		// be friendly to the level statistics. ;)
 		actor->ClearCounters();
@@ -774,13 +774,11 @@ int P_Thing_CheckProximity(AActor *self, PClass *classname, double distance, int
 		else if (classname != mo->GetClass())
 			continue;
 
-		if (mo->IsKindOf(RUNTIME_CLASS(AInventory)))
+		if (!mo->IsMapActor())
 		{
 			// Skip owned item because its position could remain unchanged since attachment to owner
 			// Most likely it is the last location of this item in the world before pick up
-			AInventory *const inventory = static_cast<AInventory*>(mo);
-			if (inventory != nullptr && inventory->Owner != nullptr)
-				continue;
+			continue;
 		}
 
 		// [MC]Make sure it's in range and respect the desire for Z or not. The function forces it to use