diff --git a/libc/include/stdlib.h b/libc/include/stdlib.h
index d0efc4c..b160e6b 100644
--- a/libc/include/stdlib.h
+++ b/libc/include/stdlib.h
@@ -114,7 +114,20 @@
  */
 __wur void* _Nullable bsearch(const void* _Nonnull __key, const void* _Nullable __base, size_t __nmemb, size_t __size, int (* _Nonnull __comparator)(const void* _Nonnull __lhs, const void* _Nonnull __rhs));
 
-void qsort(void* _Nullable __base, size_t __nmemb, size_t __size, int (* _Nonnull __comparator)(const void* _Nullable __lhs, const void* _Nullable __rhs));
+/**
+ * [qsort(3)](http://man7.org/linux/man-pages/man3/qsort.3.html) sorts an array
+ * of n elements each of the given size, using the given comparator.
+ */
+void qsort(void* _Nullable __array, size_t __n, size_t __size, int (* _Nonnull __comparator)(const void* _Nullable __lhs, const void* _Nullable __rhs));
+
+/**
+ * [qsort_r(3)](http://man7.org/linux/man-pages/man3/qsort_r.3.html) sorts an
+ * array of n elements each of the given size, using the given comparator,
+ * and passing the given context argument to the comparator.
+ *
+ * Available since API level 36.
+ */
+void qsort_r(void* _Nullable __array, size_t __n, size_t __size, int (* _Nonnull __comparator)(const void* _Nullable __lhs, const void* _Nullable __rhs, void* _Nullable __context), void* _Nullable __context) __INTRODUCED_IN(36);
 
 uint32_t arc4random(void);
 uint32_t arc4random_uniform(uint32_t __upper_bound);