include unistd which provides off_t for the header and hence unarchive applets
diff --git a/include/unarchive.h b/include/unarchive.h
index c440098..be49f3d 100644
--- a/include/unarchive.h
+++ b/include/unarchive.h
@@ -1,4 +1,5 @@
-#include <stdio.h>	// for off_t
+#include <stdio.h>	// for FILE
+#include <unistd.h>	// for off_t
 
 enum extract_functions_e {
 	extract_verbose_list = 1,