diff --git a/samples/bluetooth/hci_ipc/dts/arm/nordic/override.dtsi b/samples/bluetooth/hci_ipc/dts/arm/nordic/override.dtsi
index 51d065dee0d..31f20b802ce 100644
--- a/samples/bluetooth/hci_ipc/dts/arm/nordic/override.dtsi
+++ b/samples/bluetooth/hci_ipc/dts/arm/nordic/override.dtsi
@@ -1,2 +1,5 @@
-/* Keep default IRQ priority low for peripherals to reduce Radio ISR latency */
+/* Keep default IRQ priority low for peripherals to reduce Radio ISR latency.
+ * ARM Cortex-M4 lowest priority value of 5, i.e. considering Zephyr reserved 2
+ * levels for Exceptions and ZLI (if enabled).
+ */
 #define NRF_DEFAULT_IRQ_PRIORITY 5