diff --git a/src/shared/gatt-server.c b/src/shared/gatt-server.c
index b406ed6..bafd8de 100644
--- a/src/shared/gatt-server.c
+++ b/src/shared/gatt-server.c
}
util_debug(data->server->debug_callback, data->server->debug_data,
- "Read Multiple Req - #%lu of %lu: 0x%04x",
+ "Read Multiple Req - #%zu of %zu: 0x%04x",
data->cur_handle + 1, data->num_handles,
data->handles[data->cur_handle]);
data.handles[i] = get_le16(pdu + i * 2);
util_debug(server->debug_callback, server->debug_data,
- "Read Multiple Req - %lu handles, 1st: 0x%04x",
+ "Read Multiple Req - %zu handles, 1st: 0x%04x",
data.num_handles, data.handles[0]);
attr = gatt_db_get_attribute(server->db, data.handles[0]);