diff --git a/libuavcan/include/uavcan/internal/transport/transfer_listener.hpp b/libuavcan/include/uavcan/internal/transport/transfer_listener.hpp
index 0caa15afd0..249a824a1a 100644
--- a/libuavcan/include/uavcan/internal/transport/transfer_listener.hpp
+++ b/libuavcan/include/uavcan/internal/transport/transfer_listener.hpp
@@ -160,6 +160,7 @@ class TransferListener : public TransferListenerBase, Noncopyable
         {
             if (value.isTimedOut(ts_monotonic_))
             {
+                UAVCAN_TRACE("TransferListener", "Timed out receiver: %s", key.toString().c_str());
                 /*
                  * TransferReceivers do not own their buffers - this helps the Map<> container to copy them
                  * around quickly and safely (using default assignment operator). Downside is that we need to
diff --git a/libuavcan/src/transport/transfer_buffer.cpp b/libuavcan/src/transport/transfer_buffer.cpp
index 685d04758c..f613c36a72 100644
--- a/libuavcan/src/transport/transfer_buffer.cpp
+++ b/libuavcan/src/transport/transfer_buffer.cpp
@@ -16,7 +16,7 @@ namespace uavcan
 std::string TransferBufferManagerKey::toString() const
 {
     char buf[24];
-    std::snprintf(buf, sizeof(buf), "nid:%i tt:%i", int(node_id_), int(transfer_type_));
+    std::snprintf(buf, sizeof(buf), "nid=%i tt=%i", int(node_id_), int(transfer_type_));
     return std::string(buf);
 }