diff --git a/WinSysCore/Sid.cpp b/WinSysCore/Sid.cpp
index 5088953..81931da 100644
--- a/WinSysCore/Sid.cpp
+++ b/WinSysCore/Sid.cpp
@@ -28,8 +28,12 @@ bool Sid::IsValid()const {
 
 std::wstring Sid::AsString() const {
 	PWSTR str;
-	if (::ConvertSidToStringSid((PSID)*this,&str))
-		return str;
+	std::wstring result;
+	if (::ConvertSidToStringSid((PSID)*this, &str)) {
+		result = str;
+		::LocalFree(str);
+		return result;
+	}
 	return L"";
 }