diff --git a/src/aclic.adoc b/src/aclic.adoc
index 43e8fd4..ebb7702 100644
--- a/src/aclic.adoc
+++ b/src/aclic.adoc
@@ -284,8 +284,8 @@ External interrupt signals are supplied to the hart from the respective domain.
 The interrupts from the root domain appear as MEIP (Machine External Interrupt-Pending),
 and interrupts from the child domain appear as SEIP (Supervisor External Interrupt-Pending).
 
-In addition to signalling a pending interrupt,
-a hart-local APLIC domain singals the priority and identity of the highest priority pending-enabled interrupt to the hart.
+In addition to signaling a pending interrupt,
+a hart-local APLIC domain signals the priority and identity of the highest priority pending-enabled interrupt to the hart.
 This information is accessible at the hart through the {xtopei} CSR.
 
 === Interrupt domain control interface (Smidctrl, Ssidctrl)
@@ -738,13 +738,21 @@ The reset behavior of other fields is platform-specific.
 === Operation
 
 When {xithreshold} is a nonzero value,
-an interrupt sources _i_ at with priority number `iprio[i]`
+an interrupt source _i_ with priority number `iprio[i]`
 is considered disabled irrespective of its interrupt-enable bit,
 when the following condition holds:
 
 [source]
 ----
-iprio[i] >= xithreshold & NIPPRIO_MASK
+IPRIO >= xithreshold & NIPPRIO_MASK
+
+where IPRIO is equivalent to the value reported in xtopi CSR, i.e.
+
+1 < iprio[i] <= 255: IPRIO = iprio[i]
+255 < iprio[i]: IPRIO = 255
+iprio[i] = 0:
+  default priority higher than a machine external interrupt: IPRIO = 0
+  default priority lower than a machine external interrupt: IPRIO = 255
 ----
 
 When {xithreshold} is zero,