diff --git a/docs/design/firmware-design.rst b/docs/design/firmware-design.rst
index 84bba18..65aa4a6 100644
--- a/docs/design/firmware-design.rst
+++ b/docs/design/firmware-design.rst
@@ -1330,7 +1330,7 @@
 (priority, group, configuration). Each element of the array shall be populated
 by the macro ``INTR_PROP_DESC()``. The macro takes the following arguments:
 
-- 10-bit interrupt number,
+- 13-bit interrupt number,
 
 - 8-bit interrupt priority,