diff --git a/libc-bottom-half/headers/public/wasi/api.h b/libc-bottom-half/headers/public/wasi/api.h
index 22c4125..70be414 100644
--- a/libc-bottom-half/headers/public/wasi/api.h
+++ b/libc-bottom-half/headers/public/wasi/api.h
@@ -1169,16 +1169,20 @@ _Static_assert(offsetof(__wasi_event_fd_readwrite_t, flags) == 8, "witx calculat
 /**
  * The contents of an $event.
  */
-typedef union __wasi_event_u_t {
-    /**
-     * When type is `eventtype::fd_read` or `eventtype::fd_write`:
-     */
-    __wasi_event_fd_readwrite_t fd_readwrite;
-
+typedef union __wasi_event_u_u_t {
+    __wasi_event_fd_readwrite_t fd_read;
+    __wasi_event_fd_readwrite_t fd_write;
+} __wasi_event_u_u_t;
+typedef struct __wasi_event_u_t {
+    __wasi_eventtype_t tag;
+    __wasi_event_u_u_t u;
 } __wasi_event_u_t;
 
-_Static_assert(sizeof(__wasi_event_u_t) == 16, "witx calculated size");
+_Static_assert(sizeof(__wasi_event_u_t) == 24, "witx calculated size");
 _Static_assert(_Alignof(__wasi_event_u_t) == 8, "witx calculated align");
+_Static_assert(offsetof(__wasi_event_u_t, u) == 8, "witx calculated union offset");
+_Static_assert(sizeof(__wasi_event_u_u_t) == 16, "witx calculated union size");
+_Static_assert(_Alignof(__wasi_event_u_u_t) == 8, "witx calculated union align");
 
 /**
  * An event that occurred.
@@ -1195,22 +1199,16 @@ typedef struct __wasi_event_t {
     __wasi_errno_t error;
 
     /**
-     * The type of the event that occurred.
-     */
-    __wasi_eventtype_t type;
-
-    /**
-     * The contents of the event.
+     * The type of the event that occurred, and its contents.
      */
     __wasi_event_u_t u;
 
 } __wasi_event_t;
 
-_Static_assert(sizeof(__wasi_event_t) == 32, "witx calculated size");
+_Static_assert(sizeof(__wasi_event_t) == 40, "witx calculated size");
 _Static_assert(_Alignof(__wasi_event_t) == 8, "witx calculated align");
 _Static_assert(offsetof(__wasi_event_t, userdata) == 0, "witx calculated offset");
 _Static_assert(offsetof(__wasi_event_t, error) == 8, "witx calculated offset");
-_Static_assert(offsetof(__wasi_event_t, type) == 10, "witx calculated offset");
 _Static_assert(offsetof(__wasi_event_t, u) == 16, "witx calculated offset");
 
 /**
@@ -1284,21 +1282,21 @@ _Static_assert(offsetof(__wasi_subscription_fd_readwrite_t, file_descriptor) ==
 /**
  * The contents of a $subscription.
  */
-typedef union __wasi_subscription_u_t {
-    /**
-     * When type is `eventtype::clock`:
-     */
+typedef union __wasi_subscription_u_u_t {
     __wasi_subscription_clock_t clock;
-
-    /**
-     * When type is `eventtype::fd_read` or `eventtype::fd_write`:
-     */
-    __wasi_subscription_fd_readwrite_t fd_readwrite;
-
+    __wasi_subscription_fd_readwrite_t fd_read;
+    __wasi_subscription_fd_readwrite_t fd_write;
+} __wasi_subscription_u_u_t;
+typedef struct __wasi_subscription_u_t {
+    __wasi_eventtype_t tag;
+    __wasi_subscription_u_u_t u;
 } __wasi_subscription_u_t;
 
-_Static_assert(sizeof(__wasi_subscription_u_t) == 32, "witx calculated size");
+_Static_assert(sizeof(__wasi_subscription_u_t) == 40, "witx calculated size");
 _Static_assert(_Alignof(__wasi_subscription_u_t) == 8, "witx calculated align");
+_Static_assert(offsetof(__wasi_subscription_u_t, u) == 8, "witx calculated union offset");
+_Static_assert(sizeof(__wasi_subscription_u_u_t) == 32, "witx calculated union size");
+_Static_assert(_Alignof(__wasi_subscription_u_u_t) == 8, "witx calculated union align");
 
 /**
  * Subscription to an event.
@@ -1311,12 +1309,7 @@ typedef struct __wasi_subscription_t {
     __wasi_userdata_t userdata;
 
     /**
-     * The type of the event to which to subscribe.
-     */
-    __wasi_eventtype_t type;
-
-    /**
-     * The contents of the subscription.
+     * The type of the event to which to subscribe, and its contents
      */
     __wasi_subscription_u_t u;
 
@@ -1325,8 +1318,7 @@ typedef struct __wasi_subscription_t {
 _Static_assert(sizeof(__wasi_subscription_t) == 48, "witx calculated size");
 _Static_assert(_Alignof(__wasi_subscription_t) == 8, "witx calculated align");
 _Static_assert(offsetof(__wasi_subscription_t, userdata) == 0, "witx calculated offset");
-_Static_assert(offsetof(__wasi_subscription_t, type) == 8, "witx calculated offset");
-_Static_assert(offsetof(__wasi_subscription_t, u) == 16, "witx calculated offset");
+_Static_assert(offsetof(__wasi_subscription_t, u) == 8, "witx calculated offset");
 
 /**
  * Exit code generated by a process when exiting.
@@ -1616,40 +1608,22 @@ _Static_assert(sizeof(__wasi_prestat_dir_t) == 4, "witx calculated size");
 _Static_assert(_Alignof(__wasi_prestat_dir_t) == 4, "witx calculated align");
 _Static_assert(offsetof(__wasi_prestat_dir_t, pr_name_len) == 0, "witx calculated offset");
 
-/**
- * The contents of an $prestat.
- */
-typedef union __wasi_prestat_u_t {
-    /**
-     * When type is `preopentype::dir`:
-     */
-    __wasi_prestat_dir_t dir;
-
-} __wasi_prestat_u_t;
-
-_Static_assert(sizeof(__wasi_prestat_u_t) == 4, "witx calculated size");
-_Static_assert(_Alignof(__wasi_prestat_u_t) == 4, "witx calculated align");
-
 /**
  * Information about a pre-opened capability.
  */
+typedef union __wasi_prestat_u_t {
+    __wasi_prestat_dir_t dir;
+} __wasi_prestat_u_t;
 typedef struct __wasi_prestat_t {
-    /**
-     * The type of the pre-opened capability.
-     */
-    __wasi_preopentype_t pr_type;
-
-    /**
-     * The contents of the information.
-     */
+    __wasi_preopentype_t tag;
     __wasi_prestat_u_t u;
-
 } __wasi_prestat_t;
 
 _Static_assert(sizeof(__wasi_prestat_t) == 8, "witx calculated size");
 _Static_assert(_Alignof(__wasi_prestat_t) == 4, "witx calculated align");
-_Static_assert(offsetof(__wasi_prestat_t, pr_type) == 0, "witx calculated offset");
-_Static_assert(offsetof(__wasi_prestat_t, u) == 4, "witx calculated offset");
+_Static_assert(offsetof(__wasi_prestat_t, u) == 4, "witx calculated union offset");
+_Static_assert(sizeof(__wasi_prestat_u_t) == 4, "witx calculated union size");
+_Static_assert(_Alignof(__wasi_prestat_u_t) == 4, "witx calculated union align");
 
 /**
  * @defgroup wasi_snapshot_preview1