diff --git a/smartmontools/CHANGELOG b/smartmontools/CHANGELOG
index fddf8b8821948bd3896b58ff2e931668483d8641..a9b57ee5728b2f6decd6d97e762beac190aa9fa5 100644
--- a/smartmontools/CHANGELOG
+++ b/smartmontools/CHANGELOG
@@ -43,6 +43,8 @@ NOTES FOR FUTURE RELEASES: see TODO file.
 
 <DEVELOPERS: ADDITIONS TO THE CHANGE LOG GO JUST BELOW HERE, PLEASE>
 
+  [CF] Add USB ID of AcomData 504 (OnSpec USB bridge).
+
   [AS] Correcting manual pages (FreeBSD related)
 
   [AS] FreeBSD: fix FTBFS on GNU/kFreeBSD (reported by derevko).
diff --git a/smartmontools/scsiata.cpp b/smartmontools/scsiata.cpp
index 1b4c24da7d2622bfde14d0fdee1c79776b4be062..e87c0abdd8f194ac094486f23b3d72497aa61129 100644
--- a/smartmontools/scsiata.cpp
+++ b/smartmontools/scsiata.cpp
@@ -1415,7 +1415,9 @@ const usb_id_entry usb_ids[] = {
   // Verbatim
   { 0x18a5, 0x0215, 0x0001, d_sat     }, // Verbatim FW/USB160 - Oxford OXUF934SSA-LQAG (USB+IEE1394->SATA)
   // SunplusIT
-  { 0x1bcf, 0x0c31,     -1, d_sunplus }  // SunplusIT
+  { 0x1bcf, 0x0c31,     -1, d_sunplus }, // SunplusIT
+  // OnSpec
+  { 0x55aa, 0x2b00, 0x0100, d_unsup   }  // OnSpec ? (USB->PATA)
 };
 
 const unsigned num_usb_ids = sizeof(usb_ids)/sizeof(usb_ids[0]);