diff --git a/src/Camera/QGCCameraIO.h b/src/Camera/QGCCameraIO.h
index 6141c9b..99bf504 100644
--- a/src/Camera/QGCCameraIO.h
+++ b/src/Camera/QGCCameraIO.h
@@ -47,7 +47,7 @@ public:
     void        handleParamAck              (const mavlink_param_ext_ack_t& ack);
     void        handleParamValue            (const mavlink_param_ext_value_t& value);
     void        setParamRequest             ();
-    bool        paramDone                   () { return _done; }
+    bool        paramDone                   () const { return _done; }
     void        paramRequest                (bool reset = true);
     void        sendParameter               (bool updateUI = false);