diff --git a/boards/mulle/include/periph_conf.h b/boards/mulle/include/periph_conf.h
index bd0733ae43..8b54f45882 100644
--- a/boards/mulle/include/periph_conf.h
+++ b/boards/mulle/include/periph_conf.h
@@ -468,7 +468,7 @@ extern "C"
  * @name GPIO configuration
  * @{
  */
-#define GPIO_NUMOF          26
+#define GPIO_NUMOF          27
 #define GPIO_0_EN           1
 #define GPIO_1_EN           1
 #define GPIO_2_EN           1