diff --git a/measure.c b/measure.c
index e692ea6..7ce108e 100644
--- measure.c
+++ measure.c
@@ -14,6 +14,7 @@
 #include <string.h>
 #include <time.h>
 #include <unistd.h>
+#include <sys/types.h>
 
 #define DIR_POWERCAP "/sys/class/powercap"
 #define DIR_HWMON "/sys/class/hwmon"