diff --git a/code/espurna/mcp23s08.cpp b/code/espurna/mcp23s08.cpp
index 735de92e..a0bbaad4 100644
--- a/code/espurna/mcp23s08.cpp
+++ b/code/espurna/mcp23s08.cpp
@@ -3,9 +3,12 @@
 MCP23S08 MODULE
 
 Copyright (C) 2020 by Eddi De Pieri <eddi at depieri dot com>
-Copyright (C) 2016-2017 by Xose Pérez <xose dot perez at gmail dot com>
+
+Adapted from https://github.com/kmpelectronics/Arduino
 Copyright (C) 2016 Plamen Kovandjiev <p.kovandiev@kmpelectronics.eu> & Dimitar Antonov <d.antonov@kmpelectronics.eu>
 
+(ref. https://github.com/kmpelectronics/Arduino/blob/master/ProDinoWiFiEsp/src/PRODINoESP8266/src/KMPDinoWiFiESP.cpp)
+
 */
 
 #include "mcp23s08.h"
diff --git a/code/espurna/mcp23s08.h b/code/espurna/mcp23s08.h
index 56f712d4..3fede14c 100644
--- a/code/espurna/mcp23s08.h
+++ b/code/espurna/mcp23s08.h
@@ -2,9 +2,12 @@
 
 MCP23S08 MODULE
 
-Copyright (C) 2020-2020 by Eddi De Pieri <eddi at depieri dot com>
-Copyright (C) 2016-2017 by Xose Pérez <xose dot perez at gmail dot com>
-Copyright (C) 2016-2017 Plamen Kovandjiev <p.kovandiev@kmpelectronics.eu> & Dimitar Antonov <d.antonov@kmpelectronics.eu>
+Copyright (C) 2020 by Eddi De Pieri <eddi at depieri dot com>
+
+Adapted from https://github.com/kmpelectronics/Arduino
+Copyright (C) 2016 Plamen Kovandjiev <p.kovandiev@kmpelectronics.eu> & Dimitar Antonov <d.antonov@kmpelectronics.eu>
+
+(ref. https://github.com/kmpelectronics/Arduino/blob/master/ProDinoWiFiEsp/src/PRODINoESP8266/src/KMPDinoWiFiESP.cpp)
 
 */