diff --git a/include/linux/if_addr.h b/include/linux/if_addr.h
index d557e4c..43f3bed 100644
--- a/include/linux/if_addr.h
+++ b/include/linux/if_addr.h
@@ -39,6 +39,7 @@
 #define IFA_F_TEMPORARY		IFA_F_SECONDARY
 
 #define	IFA_F_NODAD		0x02
+#define IFA_F_OPTIMISTIC	0x04
 #define	IFA_F_HOMEADDRESS	0x10
 #define IFA_F_DEPRECATED	0x20
 #define IFA_F_TENTATIVE		0x40
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 713eb5e..e046b22 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -178,6 +178,9 @@
 #endif
 	__s32		proxy_ndp;
 	__s32		accept_source_route;
+#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
+	__s32		optimistic_dad;
+#endif
 	void		*sysctl;
 };
 
@@ -208,6 +211,7 @@
 	DEVCONF_PROXY_NDP,
 	__DEVCONF_OPTIMISTIC_DAD,
 	DEVCONF_ACCEPT_SOURCE_ROUTE,
+	DEVCONF_OPTIMISTIC_DAD,
 	DEVCONF_MAX
 };