diff --git a/pic16bit/unistd.h b/pic16bit/unistd.h
index 5b60c8a626..23c5e54c75 100644
--- a/pic16bit/unistd.h
+++ b/pic16bit/unistd.h
@@ -3,6 +3,7 @@
 
 // XC16 compiler doesn't seem to have unistd.h file
 
+#define SEEK_SET 0
 #define SEEK_CUR 1
 
 typedef int ssize_t;