diff --git a/camlibs/ptp/ptp.h b/camlibs/ptp/ptp.h
index 3e94933cb..08db8f111 100644
--- a/camlibs/ptp/ptp.h
+++ b/camlibs/ptp/ptp.h
@@ -202,7 +202,7 @@ short ptp_closesession (PTPParams *params);
 
 short ptp_getobjecthandles (PTPParams *params, PTPObjectHandles* objecthandles);
 short ptp_getobjectinfo   (PTPParams *params, PTPObjectHandles* objecthandles,
-			    PTPObjectInfo** objectinfoarray, int n);
+			    int n, PTPObjectInfo** objectinfoarray);
 short ptp_getobject        (PTPParams *params, PTPObjectHandles* objecthandles,
 			    PTPObjectInfo* objectinfoarray, int n,
 			    char* object);