diff --git a/cores/arduino/wiring_analog.h b/cores/arduino/wiring_analog.h
index 006e5b94a827f1f2c106998cf95e1357125cef73..c02ac7fdf631ef31d3bd18c7818417f7343a1e15 100644
--- a/cores/arduino/wiring_analog.h
+++ b/cores/arduino/wiring_analog.h
@@ -31,8 +31,8 @@ extern "C" {
 typedef enum _eAnalogReference
 {
   AR_DEFAULT,
-  INTERNAL,
-  EXTERNAL
+  AR_INTERNAL,
+  AR_EXTERNAL
 } eAnalogReference ;