diff --git a/src/FileSink.cpp b/src/FileSink.cpp
index 51afef6..1cb9f6c 100644
--- a/src/FileSink.cpp
+++ b/src/FileSink.cpp
@@ -53,14 +53,16 @@ FileSink::FileSink(AbsPathView filepath, Mode mode, Flags flags) noexcept
 	{
 	case Mode::CreateOrOpen:
 		fmode |= fast_io::open_mode::creat;
-		// fall through
+		break;
 	case Mode::Open:
 		break;
 	case Mode::CreateOrOpenAndClear:
-		fmode |= fast_io::open_mode::creat;
-		// fall through
+		//fmode |= fast_io::open_mode::creat; //cannot pass this, seems like a bug in fast_io. If it's passed, the mode reverts to OPEN_ALWAYS
+		fmode |= fast_io::open_mode::trunc;
+		break;
 	case Mode::OpenAndClear:
 		fmode |= fast_io::open_mode::trunc;
+		fmode |= fast_io::open_mode::excl;
 		break;
 	case Mode::CreateIfNew:
 		fmode |= fast_io::open_mode::creat;