diff --git a/examples/stm32/f4/stm32f4-discovery/README.md b/examples/stm32/f4/stm32f4-discovery/README.md
index f91a184..c0286dc 100644
--- a/examples/stm32/f4/stm32f4-discovery/README.md
+++ b/examples/stm32/f4/stm32f4-discovery/README.md
@@ -1,7 +1,7 @@
 # README
 
 This directory contains examples for the _original_ stm32f4 discovery.
-The PCB should be labelled either MB997A or MB997B, and contains a user USB
+The PCB should be labelled as MB997{A,B,C}, and contains a user USB
 port, and an audio dac on board, along with a MEMs microphone and an
 accelerometer.