diff --git a/nimble/controller/test/syscfg.yml b/nimble/controller/test/syscfg.yml
index 979e7a026..217575c09 100644
--- a/nimble/controller/test/syscfg.yml
+++ b/nimble/controller/test/syscfg.yml
@@ -20,3 +20,6 @@
 
 syscfg.vals:
     BLE_LL_CFG_FEAT_LE_CSA2: 1
+
+    # Prevent priority conflict with controller task.
+    MCU_UART_POLLER_PRIO: 16