diff --git a/doc/system.tex b/doc/system.tex
index be157766..54f35b1f 100644
--- a/doc/system.tex
+++ b/doc/system.tex
@@ -253,7 +253,9 @@ \section{IRQ map}
 \hline
 10 & Texture Mapping Unit\\
 \hline
-11 & PS/2 (ML401 only)\\
+11 & PS/2 keyboard (ML401 only)\\
+\hline
+12 & PS/2 mouse (ML401 only)\\
 \hline
 \end{tabularx}