diff --git a/xroot_plugins/XrdSsiCtaRequestMessage.cpp b/xroot_plugins/XrdSsiCtaRequestMessage.cpp
index 44412a407c054a8220a7150d5b9847e3fb6c3e9a..2b983f7ce5eef6870b2e2c91e7190193af14711c 100644
--- a/xroot_plugins/XrdSsiCtaRequestMessage.cpp
+++ b/xroot_plugins/XrdSsiCtaRequestMessage.cpp
@@ -335,7 +335,7 @@ void RequestMessage::processCLOSEW(const cta::eos::Notification &notification, c
    request.checksumType     = checksumtype;
    request.checksumValue    = checksumvalue;
    request.diskFileInfo     = diskFileInfo;
-   request.diskFileID       = notification.file().fid();
+   request.diskFileID       = std::to_string(notification.file().fid());
    request.fileSize         = notification.file().size();
    request.requester        = originator;
    request.srcURL           = notification.wf().instance().url();