diff --git a/rpieepromab/main.c b/rpieepromab/main.c
index 0b64b68..1324063 100644
--- a/rpieepromab/main.c
+++ b/rpieepromab/main.c
@@ -1,3 +1,4 @@
+#define _GNU_SOURCE
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>