diff --git a/src/scripting/codegeneration/codegen.cpp b/src/scripting/codegeneration/codegen.cpp
index 61b23cc158..fa9fe13c9b 100644
--- a/src/scripting/codegeneration/codegen.cpp
+++ b/src/scripting/codegeneration/codegen.cpp
@@ -8101,11 +8101,27 @@ FxExpression *FxRuntimeStateIndex::Resolve(FCompileContext &ctx)
 		delete this;
 		return nullptr;
 	}
-	else if (Index->isConstant() && static_cast<FxConstant *>(Index)->GetValue().GetInt() <= 0)
+	else if (Index->isConstant())
 	{
-		ScriptPosition.Message(MSG_ERROR, "State index must be positive");
-		delete this;
-		return nullptr;
+		int index = static_cast<FxConstant *>(Index)->GetValue().GetInt();
+		if (index < 0 || (index == 0 && !ctx.FromDecorate))
+		{
+			ScriptPosition.Message(MSG_ERROR, "State index must be positive");
+			delete this;
+			return nullptr;
+		}
+		else if (index == 0)
+		{
+			auto x = new FxConstant((FState*)nullptr, ScriptPosition);
+			delete this;
+			return x->Resolve(ctx);
+		}
+		else
+		{
+			auto x = new FxStateByIndex(index, ScriptPosition);
+			delete this;
+			return x->Resolve(ctx);
+		}
 	}
 	else if (Index->ValueType->GetRegType() != REGT_INT)
 	{ // Float.
diff --git a/src/scripting/decorate/thingdef_parse.cpp b/src/scripting/decorate/thingdef_parse.cpp
index b344a12283..4308950600 100644
--- a/src/scripting/decorate/thingdef_parse.cpp
+++ b/src/scripting/decorate/thingdef_parse.cpp
@@ -181,15 +181,11 @@ FxExpression *ParseParameter(FScanner &sc, PClassActor *cls, PType *type, bool c
 		{
 			if (sc.String[0] == 0 || sc.Compare("None"))
 			{
-				x = new FxConstant((FState*)NULL, sc);
+				x = new FxConstant((FState*)nullptr, sc);
 			}
 			else if (sc.Compare("*"))
 			{
-				if (constant)
-				{
-					x = new FxConstant((FState*)(intptr_t)-1, sc);
-				}
-				else sc.ScriptError("Invalid state name '*'");
+				sc.ScriptError("Invalid state name '*'");
 			}
 			else
 			{