diff --git a/src/system/kernel/device_manager/IORequest.cpp b/src/system/kernel/device_manager/IORequest.cpp
index 9c38a0a104..eb93c1c5c8 100644
--- a/src/system/kernel/device_manager/IORequest.cpp
+++ b/src/system/kernel/device_manager/IORequest.cpp
@@ -1093,6 +1093,8 @@ IORequest::SetTransferredBytes(bool partialTransfer,
 
 	MutexLocker _(fLock);
 
+	ASSERT(transferredBytes <= fLength);
+
 	fPartialTransfer = partialTransfer;
 	fTransferSize = transferredBytes;
 }