--- a/source/c_gpio/c_gpio.h.orig
+++ b/source/c_gpio/c_gpio.h
@@ -30,6 +30,8 @@
 int gpio_function(int gpio);
 void set_pullupdn(int gpio, int pud);
 
+#include <sys/types.h>
+
 #define SETUP_OK          0
 #define SETUP_DEVMEM_FAIL 1
 #define SETUP_MALLOC_FAIL 2