diff --git a/src/doc/unstable-book/src/library-features/debug-map-key-value.md b/src/doc/unstable-book/src/library-features/debug-map-key-value.md
deleted file mode 100644
index ae839bf2ac3..00000000000
--- a/src/doc/unstable-book/src/library-features/debug-map-key-value.md
+++ /dev/null
@@ -1,9 +0,0 @@
-# `debug_map_key_value`
-
-The tracking issue for this feature is: [#62482]
-
-[#62482]: https://github.com/rust-lang/rust/issues/62482
-
-------------------------
-
-Add the methods `key` and `value` to `DebugMap` so that an entry can be formatted across multiple calls without additional buffering.
diff --git a/src/libcore/fmt/builders.rs b/src/libcore/fmt/builders.rs
index 8ba0e422e8f..63866a5d110 100644
--- a/src/libcore/fmt/builders.rs
+++ b/src/libcore/fmt/builders.rs
@@ -778,7 +778,6 @@ impl<'a, 'b: 'a> DebugMap<'a, 'b> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(debug_map_key_value)]
     /// use std::fmt;
     ///
     /// struct Foo(Vec<(String, i32)>);
@@ -796,7 +795,7 @@ impl<'a, 'b: 'a> DebugMap<'a, 'b> {
     ///     "{\"whole\": [(\"A\", 10), (\"B\", 11)]}",
     /// );
     /// ```
-    #[unstable(feature = "debug_map_key_value", reason = "recently added", issue = "62482")]
+    #[stable(feature = "debug_map_key_value", since = "1.42.0")]
     pub fn key(&mut self, key: &dyn fmt::Debug) -> &mut Self {
         self.result = self.result.and_then(|_| {
             assert!(
@@ -843,7 +842,6 @@ impl<'a, 'b: 'a> DebugMap<'a, 'b> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(debug_map_key_value)]
     /// use std::fmt;
     ///
     /// struct Foo(Vec<(String, i32)>);
@@ -861,7 +859,7 @@ impl<'a, 'b: 'a> DebugMap<'a, 'b> {
     ///     "{\"whole\": [(\"A\", 10), (\"B\", 11)]}",
     /// );
     /// ```
-    #[unstable(feature = "debug_map_key_value", reason = "recently added", issue = "62482")]
+    #[stable(feature = "debug_map_key_value", since = "1.42.0")]
     pub fn value(&mut self, value: &dyn fmt::Debug) -> &mut Self {
         self.result = self.result.and_then(|_| {
             assert!(self.has_key, "attempted to format a map value before its key");
diff --git a/src/libcore/tests/lib.rs b/src/libcore/tests/lib.rs
index 21e279066e7..197536158be 100644
--- a/src/libcore/tests/lib.rs
+++ b/src/libcore/tests/lib.rs
@@ -4,7 +4,6 @@
 #![feature(cell_update)]
 #![feature(core_private_bignum)]
 #![feature(core_private_diy_float)]
-#![feature(debug_map_key_value)]
 #![feature(debug_non_exhaustive)]
 #![feature(dec2flt)]
 #![feature(exact_size_is_empty)]