diff --git a/libc/include/sys/statvfs.h b/libc/include/sys/statvfs.h
index 793ee13..d81f836 100644
--- a/libc/include/sys/statvfs.h
+++ b/libc/include/sys/statvfs.h
@@ -96,7 +96,7 @@
  *
  * Available since API level 19.
  */
-int statvfs(const char* __path, struct statvfs* __buf) __INTRODUCED_IN(19);
+int statvfs(const char* _Nonnull __path, struct statvfs* _Nonnull __buf) __INTRODUCED_IN(19);
 
 /**
  * [fstatvfs(3)](http://man7.org/linux/man-pages/man3/fstatvfs.3.html)
@@ -106,12 +106,12 @@
  *
  * Available since API level 19.
  */
-int fstatvfs(int __fd, struct statvfs* __buf) __INTRODUCED_IN(19);
+int fstatvfs(int __fd, struct statvfs* _Nonnull __buf) __INTRODUCED_IN(19);
 
 /** Equivalent to statvfs() . */
-int statvfs64(const char* __path, struct statvfs64* __buf) __INTRODUCED_IN(21);
+int statvfs64(const char* _Nonnull __path, struct statvfs64* _Nonnull __buf) __INTRODUCED_IN(21);
 
 /** Equivalent to fstatvfs(). */
-int fstatvfs64(int __fd, struct statvfs64* __buf) __INTRODUCED_IN(21);
+int fstatvfs64(int __fd, struct statvfs64* _Nonnull __buf) __INTRODUCED_IN(21);
 
 __END_DECLS