diff --git a/libc/include/ucontext.h b/libc/include/ucontext.h
index 73c2166..99201d2 100644
--- a/libc/include/ucontext.h
+++ b/libc/include/ucontext.h
@@ -1 +1,10 @@
+#pragma once
+
+/**
+ * @file ucontext.h
+ * @brief Historical alternative to `<sys/ucontext.h>`.
+ *
+ * New code should use `<sys/ucontext.h>` directly.
+ */
+
 #include <sys/ucontext.h>