diff --git a/include/adclib/adclib_device1.h b/include/adclib/adclib_device1.h
index 9a4aaba..999cca4 100644
--- a/include/adclib/adclib_device1.h
+++ b/include/adclib/adclib_device1.h
@@ -202,7 +202,7 @@ protected:
                 if (setter.value()) {
                     return setter.value()(std::forward<VT>(val));
                 } else {
-                    return AdcDeviceErrorCode::ERROR_WO_ATTR;
+                    return AdcDeviceErrorCode::ERROR_RO_ATTR;
                 }
             }
 
@@ -227,7 +227,6 @@ protected:
     snplib::hmap<ATTR_ID_T> _attrGetter{};
     snplib::hmap<ATTR_ID_T> _attrSetter{};
 
-
     // default convert functions for char-range types
 
     template <typename VR, typename UR>
@@ -478,7 +477,7 @@ public:
                     std::forward_as_tuple(id, attr_setter_t<v_t>(std::forward<decltype(setter_cap)>(setter_cap))),
                     std::tuple_cat(std::forward_as_tuple(st_cnv_from_func.template operator()<2 * Is>(),
                                                          st_cnv_to_func.template operator()<2 * Is>())...)));
-        }(std::make_index_sequence<std::tuple_size_v<AdcGenericDevice::char_ranges_t>>{});
+        }(std::make_index_sequence<NFUNCS / 2>{});
 
         return;