diff --git a/include/proxy/http3/Http3Transaction.h b/include/proxy/http3/Http3Transaction.h
index abb7dfd6359..d911967ff17 100644
--- a/include/proxy/http3/Http3Transaction.h
+++ b/include/proxy/http3/Http3Transaction.h
@@ -74,6 +74,17 @@ class HQTransaction : public ProxyTransaction
   virtual int             state_stream_closed(int event, Event *data) = 0;
   NetVConnectionContext_t direction() const;
 
+  /** Full-width QUIC stream identifier for this transaction.
+   *
+   *  @c get_transaction_id returns @c int and exists primarily for compact log
+   *  fields and probe arguments; QUIC stream IDs are 62-bit values, so callers
+   *  that route or compare by stream ID must use this accessor to avoid
+   *  truncation.
+   *
+   *  @return The QUIC stream ID owned by this transaction.
+   */
+  QUICStreamId get_quic_stream_id() const;
+
   // For Queue from tscore/Link.h
   LINK(HQTransaction, link);
 
diff --git a/src/proxy/http3/Http3Session.cc b/src/proxy/http3/Http3Session.cc
index 4c899f2e37f..1ec5a09d161 100644
--- a/src/proxy/http3/Http3Session.cc
+++ b/src/proxy/http3/Http3Session.cc
@@ -97,7 +97,7 @@ HQTransaction *
 HQSession::get_transaction(QUICStreamId id)
 {
   for (HQTransaction *t = this->_transaction_list.head; t; t = static_cast<HQTransaction *>(t->link.next)) {
-    if (t->get_transaction_id() == static_cast<int>(id)) {
+    if (t->get_quic_stream_id() == id) {
       return t;
     }
   }
diff --git a/src/proxy/http3/Http3Transaction.cc b/src/proxy/http3/Http3Transaction.cc
index 44b2c828ef7..b2a818029f8 100644
--- a/src/proxy/http3/Http3Transaction.cc
+++ b/src/proxy/http3/Http3Transaction.cc
@@ -225,6 +225,13 @@ HQTransaction::transaction_done()
 
 int
 HQTransaction::get_transaction_id() const
+{
+  // Narrowing is intentional here; see get_quic_stream_id() for the full-width value.
+  return static_cast<int>(this->_stream_id);
+}
+
+QUICStreamId
+HQTransaction::get_quic_stream_id() const
 {
   return this->_stream_id;
 }