diff --git a/libc/include/sys/uio.h b/libc/include/sys/uio.h
index 583cfc6..c8c64ae 100644
--- a/libc/include/sys/uio.h
+++ b/libc/include/sys/uio.h
@@ -46,7 +46,7 @@
  * Returns the number of bytes read on success,
  * and returns -1 and sets `errno` on failure.
  */
-ssize_t readv(int __fd, const struct iovec* __iov, int __count);
+ssize_t readv(int __fd, const struct iovec* _Nonnull __iov, int __count);
 
 /**
  * [writev(2)](http://man7.org/linux/man-pages/man2/writev.2.html) writes
@@ -55,7 +55,7 @@
  * Returns the number of bytes written on success,
  * and returns -1 and sets `errno` on failure.
  */
-ssize_t writev(int __fd, const struct iovec* __iov, int __count);
+ssize_t writev(int __fd, const struct iovec* _Nonnull __iov, int __count);
 
 #if defined(__USE_GNU)
 
@@ -69,7 +69,7 @@
  *
  * Available since API level 24.
  */
-ssize_t preadv(int __fd, const struct iovec* __iov, int __count, off_t __offset) __RENAME_IF_FILE_OFFSET64(preadv64) __INTRODUCED_IN(24);
+ssize_t preadv(int __fd, const struct iovec* _Nonnull __iov, int __count, off_t __offset) __RENAME_IF_FILE_OFFSET64(preadv64) __INTRODUCED_IN(24);
 
 /**
  * [pwritev(2)](http://man7.org/linux/man-pages/man2/pwritev.2.html) writes
@@ -81,21 +81,21 @@
  *
  * Available since API level 24.
  */
-ssize_t pwritev(int __fd, const struct iovec* __iov, int __count, off_t __offset) __RENAME_IF_FILE_OFFSET64(pwritev64) __INTRODUCED_IN(24);
+ssize_t pwritev(int __fd, const struct iovec* _Nonnull __iov, int __count, off_t __offset) __RENAME_IF_FILE_OFFSET64(pwritev64) __INTRODUCED_IN(24);
 
 /**
  * Like preadv() but with a 64-bit offset even in a 32-bit process.
  *
  * Available since API level 24.
  */
-ssize_t preadv64(int __fd, const struct iovec* __iov, int __count, off64_t __offset) __INTRODUCED_IN(24);
+ssize_t preadv64(int __fd, const struct iovec* _Nonnull __iov, int __count, off64_t __offset) __INTRODUCED_IN(24);
 
 /**
  * Like pwritev() but with a 64-bit offset even in a 32-bit process.
  *
  * Available since API level 24.
  */
-ssize_t pwritev64(int __fd, const struct iovec* __iov, int __count, off64_t __offset) __INTRODUCED_IN(24);
+ssize_t pwritev64(int __fd, const struct iovec* _Nonnull __iov, int __count, off64_t __offset) __INTRODUCED_IN(24);
 
 /**
  * [preadv2(2)](http://man7.org/linux/man-pages/man2/preadv2.2.html) reads
@@ -107,7 +107,7 @@
  *
  * Available since API level 33.
  */
-ssize_t preadv2(int __fd, const struct iovec* __iov, int __count, off_t __offset, int __flags) __RENAME_IF_FILE_OFFSET64(preadv64v2) __INTRODUCED_IN(33);
+ssize_t preadv2(int __fd, const struct iovec* _Nonnull __iov, int __count, off_t __offset, int __flags) __RENAME_IF_FILE_OFFSET64(preadv64v2) __INTRODUCED_IN(33);
 
 /**
  * [pwritev2(2)](http://man7.org/linux/man-pages/man2/pwritev2.2.html) writes
@@ -119,21 +119,21 @@
  *
  * Available since API level 33.
  */
-ssize_t pwritev2(int __fd, const struct iovec* __iov, int __count, off_t __offset, int __flags) __RENAME_IF_FILE_OFFSET64(pwritev64v2) __INTRODUCED_IN(33);
+ssize_t pwritev2(int __fd, const struct iovec* _Nonnull __iov, int __count, off_t __offset, int __flags) __RENAME_IF_FILE_OFFSET64(pwritev64v2) __INTRODUCED_IN(33);
 
 /**
  * Like preadv2() but with a 64-bit offset even in a 32-bit process.
  *
  * Available since API level 33.
  */
-ssize_t preadv64v2(int __fd, const struct iovec* __iov, int __count, off64_t __offset, int __flags) __INTRODUCED_IN(33);
+ssize_t preadv64v2(int __fd, const struct iovec* _Nonnull __iov, int __count, off64_t __offset, int __flags) __INTRODUCED_IN(33);
 
 /**
  * Like pwritev2() but with a 64-bit offset even in a 32-bit process.
  *
  * Available since API level 33.
  */
-ssize_t pwritev64v2(int __fd, const struct iovec* __iov, int __count, off64_t __offset, int __flags) __INTRODUCED_IN(33);
+ssize_t pwritev64v2(int __fd, const struct iovec* _Nonnull __iov, int __count, off64_t __offset, int __flags) __INTRODUCED_IN(33);
 
 /**
  * [process_vm_readv(2)](http://man7.org/linux/man-pages/man2/process_vm_readv.2.html)
@@ -144,7 +144,7 @@
  *
  * Available since API level 23.
  */
-ssize_t process_vm_readv(pid_t __pid, const struct iovec* __local_iov, unsigned long __local_iov_count, const struct iovec* __remote_iov, unsigned long __remote_iov_count, unsigned long __flags) __INTRODUCED_IN(23);
+ssize_t process_vm_readv(pid_t __pid, const struct iovec* __BIONIC_COMPLICATED_NULLNESS __local_iov, unsigned long __local_iov_count, const struct iovec* __BIONIC_COMPLICATED_NULLNESS __remote_iov, unsigned long __remote_iov_count, unsigned long __flags) __INTRODUCED_IN(23);
 
 /**
  * [process_vm_writev(2)](http://man7.org/linux/man-pages/man2/process_vm_writev.2.html)
@@ -155,7 +155,7 @@
  *
  * Available since API level 23.
  */
-ssize_t process_vm_writev(pid_t __pid, const struct iovec* __local_iov, unsigned long __local_iov_count, const struct iovec* __remote_iov, unsigned long __remote_iov_count, unsigned long __flags) __INTRODUCED_IN(23);
+ssize_t process_vm_writev(pid_t __pid, const struct iovec* __BIONIC_COMPLICATED_NULLNESS __local_iov, unsigned long __local_iov_count, const struct iovec* __BIONIC_COMPLICATED_NULLNESS __remote_iov, unsigned long __remote_iov_count, unsigned long __flags) __INTRODUCED_IN(23);
 
 #endif