diff --git a/src/sys/README b/src/sys/README
index ea1d942..fdae3e6 100644
--- a/src/sys/README
+++ b/src/sys/README
@@ -8,6 +8,7 @@
   isa     - ISA drivers
   kernel  - Kernel code (things not directly connected with the system)
   lib     - Kernel library
+  mpi     - Message passing interface code
   net     - Networking subsystem code (LwIP)
   pci     - PCI drivers and subsystem
   sde     - Screen drawing engine code