diff --git a/libraries/AP_Proximity/AP_Proximity.h b/libraries/AP_Proximity/AP_Proximity.h
index 548766b73c..8df5f2a521 100644
--- a/libraries/AP_Proximity/AP_Proximity.h
+++ b/libraries/AP_Proximity/AP_Proximity.h
@@ -102,7 +102,7 @@ public:
     };
 
     // detect and initialise any available proximity sensors
-    void init();
+    __INITFUNC__ void init();
 
     // update state of all proximity sensors. Should be called at high rate from main loop
     void update();