diff --git a/include/ble_utils/ble_utils.hpp b/include/ble_utils/ble_utils.hpp
index 24527c9..16e779e 100644
--- a/include/ble_utils/ble_utils.hpp
+++ b/include/ble_utils/ble_utils.hpp
@@ -62,10 +62,11 @@ class Characteristic
      * @return Number of bytes read, or in case of an error
      *          BT_GATT_ERR() with a specific BT_ATT_ERR_* error code.
      */
-    virtual ssize_t read_cb(void *buf, uint16_t len)
+    virtual ssize_t read_cb(void *buf, uint16_t len, uint16_t offset)
     {
         ARG_UNUSED(buf);
         ARG_UNUSED(len);
+        ARG_UNUSED(offset);
         return 0;
     };
 
@@ -78,10 +79,12 @@ class Characteristic
     *  @return Number of bytes written, or in case of an error
     *          BT_GATT_ERR() with a specific BT_ATT_ERR_* error code.
     */
-    virtual ssize_t write_cb(const void *buf,uint16_t len)
+    virtual ssize_t write_cb(const void *buf,uint16_t len, uint16_t offset, uint8_t flags)
     {
         ARG_UNUSED(buf);
         ARG_UNUSED(len);
+        ARG_UNUSED(offset);
+        ARG_UNUSED(flags);
         return 0;
     }
 
diff --git a/samples/uptime/src/uptime_service.cpp b/samples/uptime/src/uptime_service.cpp
index eab680b..d78d95e 100644
--- a/samples/uptime/src/uptime_service.cpp
+++ b/samples/uptime/src/uptime_service.cpp
@@ -29,8 +29,9 @@ Basic::Basic():
 {
 }
 
-ssize_t Basic::read_cb(void *buf, uint16_t len)
+ssize_t Basic::read_cb(void *buf, uint16_t len, uint16_t offset)
 {
+    ARG_UNUSED(offset);
     uint8_t * pUptime = static_cast<uint8_t*>(buf);
     pUptime[0] = m_uptime & 0xFF;
     pUptime[1] = m_uptime>>8 & 0xFF;
diff --git a/samples/uptime/src/uptime_service.hpp b/samples/uptime/src/uptime_service.hpp
index d8fb254..c1899ed 100644
--- a/samples/uptime/src/uptime_service.hpp
+++ b/samples/uptime/src/uptime_service.hpp
@@ -42,7 +42,7 @@ class Basic final: public ble_utils::gatt::Characteristic
     Basic();
     void update(uint32_t uptime);
 private:
-    ssize_t read_cb(void *buf, uint16_t len) override;
+    ssize_t read_cb(void *buf, uint16_t len, uint16_t offset) override;
     uint32_t m_uptime{0};
 };
 
diff --git a/src/ble_utils.cpp b/src/ble_utils.cpp
index 7b3790e..997fcfd 100644
--- a/src/ble_utils.cpp
+++ b/src/ble_utils.cpp
@@ -66,9 +66,8 @@ ssize_t Characteristic::_read_cb(struct bt_conn *conn,
                     uint16_t offset)
 {
     ARG_UNUSED(conn);
-    ARG_UNUSED(offset);
     auto instance = static_cast<Characteristic *>(attr->user_data);
-    return instance->read_cb(buf, len);
+    return instance->read_cb(buf, len, offset);
 }
 ssize_t Characteristic::_write_cb(struct bt_conn *conn,
                             const struct bt_gatt_attr *attr,
@@ -78,10 +77,8 @@ ssize_t Characteristic::_write_cb(struct bt_conn *conn,
                             uint8_t flags)
 {
     ARG_UNUSED(conn);
-    ARG_UNUSED(offset);
-    ARG_UNUSED(flags);
     auto instance = static_cast<Characteristic *>(attr->user_data);
-    return instance->write_cb(buf, len);
+    return instance->write_cb(buf, len, offset, flags);
 }
 
 Service::Service(const bt_uuid *uuid):
@@ -112,6 +109,7 @@ void Service::register_char(const Characteristic * chrc)
                                     ICharacteristicCCC::attr_size
                                     : Characteristic::attr_size;
     const auto req_size{m_gatt_service.attr_count + chrc_attr_size};
+    ARG_UNUSED(req_size);
     __ASSERT(req_size <= MAX_ATTR, "Max. attribute size reached");
     attrs[m_gatt_service.attr_count++] = chrc->m_attr;
     attrs[m_gatt_service.attr_count++] = chrc->m_attr_value;