diff --git a/README.md b/README.md
index 2cc65cb..40f5f8d 100644
--- a/README.md
+++ b/README.md
@@ -17,6 +17,8 @@ Example: 12201
 01 - specific error code: Heatbed heating failed
 
 ## Printer number
+04 - Original Prusa MMU
+
 10 - Original Prusa SL1/SL1S
 
 12 - Original Prusa MINI/MINI+