diff --git a/src/common/scripting/backend/codegen.cpp b/src/common/scripting/backend/codegen.cpp
index a450ceb59..5bedaea4f 100644
--- a/src/common/scripting/backend/codegen.cpp
+++ b/src/common/scripting/backend/codegen.cpp
@@ -4378,7 +4378,7 @@ ExpEmit FxConcat::Emit(VMFunctionBuilder *build)
 			build->Emit(op2.RegType == REGT_INT ? OP_LK : op2.RegType == REGT_FLOAT ? OP_LKF : OP_LKP, nonconst.RegNum, op2.RegNum);
 			op2 = nonconst;
 		}
-		if (op1.RegType == REGT_FLOAT) cast = op1.RegCount == 1 ? CAST_F2S : op1.RegCount == 2 ? CAST_V22S : op1.RegCount == 3 ? CAST_V32S : CAST_V42S;
+		if (op2.RegType == REGT_FLOAT) cast = op2.RegCount == 1 ? CAST_F2S : op2.RegCount == 2 ? CAST_V22S : op2.RegCount == 3 ? CAST_V32S : CAST_V42S;
 		else if (right->ValueType == TypeUInt32) cast = CAST_U2S;
 		else if (right->ValueType == TypeName) cast = CAST_N2S;
 		else if (right->ValueType == TypeSound) cast = CAST_So2S;