diff --git a/fs/fs.c b/fs/fs.c
index 779f264..9a79a03 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -1590,6 +1590,9 @@
 		case 4:
 			*((ulong  *)dst) = *((ulong  *)src);
 			break;
+		case 8:
+			*((u64  *)dst) = *((u64  *)src);
+			break;
 		}
 		dst += rwsize;
 		src += rwsize;
diff --git a/include/fcntl.h b/include/fcntl.h
index aed741e..501b415 100644
--- a/include/fcntl.h
+++ b/include/fcntl.h
@@ -17,11 +17,12 @@
 #define O_NOFOLLOW	00400000	/* don't follow links */
 
 /* barebox additional flags */
-#define O_RWSIZE_MASK	00000070
+#define O_RWSIZE_MASK	00000170
 #define O_RWSIZE_SHIFT	3
 #define O_RWSIZE_1      00000010
 #define O_RWSIZE_2      00000020
 #define O_RWSIZE_4      00000040
+#define O_RWSIZE_8      00000100
 
 #define F_DUPFD		0	/* dup */
 #define F_GETFD		1	/* get close_on_exec */