diff --git a/doc/api-extensions.md b/doc/api-extensions.md
index 9a716e48a..40270fa7b 100644
--- a/doc/api-extensions.md
+++ b/doc/api-extensions.md
@@ -140,3 +140,7 @@ the container.
 ## seccomp\_notify\_fd\_active
 
 Retrieve the seccomp notifier fd from a running container.
+
+## seccomp\_proxy\_send\_notify\_fd
+
+Whether the seccomp notify proxy sends a long a notify fd file descriptor.
diff --git a/src/lxc/api_extensions.h b/src/lxc/api_extensions.h
index 1b40e5d45..826781272 100644
--- a/src/lxc/api_extensions.h
+++ b/src/lxc/api_extensions.h
@@ -45,6 +45,7 @@ static char *api_extensions[] = {
 	"seccomp_allow_deny_syntax",
 	"devpts_fd",
 	"seccomp_notify_fd_active",
+	"seccomp_proxy_send_notify_fd",
 };
 
 static size_t nr_api_extensions = sizeof(api_extensions) / sizeof(*api_extensions);