diff --git a/include/asm-generic/fcntl.h b/include/asm-generic/fcntl.h
index e3cbc38..a70b2d2 100644
--- a/include/asm-generic/fcntl.h
+++ b/include/asm-generic/fcntl.h
@@ -11,6 +11,10 @@
  * -Eric Paris
  */
 
+/*
+ * When introducing new O_* bits, please check its uniqueness in fcntl_init().
+ */
+
 #define O_ACCMODE	00000003
 #define O_RDONLY	00000000
 #define O_WRONLY	00000001