diff --git a/changes/bug40878 b/changes/bug40878
new file mode 100644
index 0000000000..503ace69da
--- /dev/null
+++ b/changes/bug40878
@@ -0,0 +1,4 @@
+  o Minor bugfixes (vanguards addon support):
+    - Count the conflux linked cell as valid when it is successfully
+      processed. This will quiet a spurious warn in the vanguards addon.
+      Fixes bug 40878; bugfix on 0.4.8.1-alpha.
diff --git a/src/core/or/conflux_pool.c b/src/core/or/conflux_pool.c
index 4a7e941372..3a8f6ec8e3 100644
--- a/src/core/or/conflux_pool.c
+++ b/src/core/or/conflux_pool.c
@@ -1975,6 +1975,9 @@ conflux_process_linked(circuit_t *circ, crypt_path_t *layer_hint,
     connection_ap_attach_pending(1);
   }
 
+  /* This cell is now considered valid for clients. */
+  circuit_read_valid_data(TO_ORIGIN_CIRCUIT(circ), cell_len);
+
   goto end;
 
  close: