diff --git a/targets/targets.json b/targets/targets.json
index 45c19fd313..9a5edf566e 100644
--- a/targets/targets.json
+++ b/targets/targets.json
@@ -1507,6 +1507,7 @@
             "PORTINOUT",
             "PORTOUT",
             "PWMOUT",
+            "RESET_REASON",
             "SERIAL",
             "SERIAL_FC",
             "SERIAL_ASYNCH",