diff --git a/src/libstd/lib.rs b/src/libstd/lib.rs
index c3882bacf87eb..71050b0dcd1f5 100644
--- a/src/libstd/lib.rs
+++ b/src/libstd/lib.rs
@@ -244,7 +244,6 @@
 #![feature(cfg_target_has_atomic)]
 #![feature(cfg_target_thread_local)]
 #![feature(char_error_internals)]
-#![feature(checked_duration_since)]
 #![feature(clamp)]
 #![feature(compiler_builtins_lib)]
 #![feature(concat_idents)]
diff --git a/src/libstd/time.rs b/src/libstd/time.rs
index 98371b9ba3d7e..d59085cd44a6f 100644
--- a/src/libstd/time.rs
+++ b/src/libstd/time.rs
@@ -221,7 +221,6 @@ impl Instant {
     /// # Examples
     ///
     /// ```no_run
-    /// #![feature(checked_duration_since)]
     /// use std::time::{Duration, Instant};
     /// use std::thread::sleep;
     ///
@@ -231,7 +230,7 @@ impl Instant {
     /// println!("{:?}", new_now.checked_duration_since(now));
     /// println!("{:?}", now.checked_duration_since(new_now)); // None
     /// ```
-    #[unstable(feature = "checked_duration_since", issue = "58402")]
+    #[stable(feature = "checked_duration_since", since = "1.39.0")]
     pub fn checked_duration_since(&self, earlier: Instant) -> Option<Duration> {
         self.0.checked_sub_instant(&earlier.0)
     }
@@ -242,7 +241,6 @@ impl Instant {
     /// # Examples
     ///
     /// ```no_run
-    /// #![feature(checked_duration_since)]
     /// use std::time::{Duration, Instant};
     /// use std::thread::sleep;
     ///
@@ -252,7 +250,7 @@ impl Instant {
     /// println!("{:?}", new_now.saturating_duration_since(now));
     /// println!("{:?}", now.saturating_duration_since(new_now)); // 0ns
     /// ```
-    #[unstable(feature = "checked_duration_since", issue = "58402")]
+    #[stable(feature = "checked_duration_since", since = "1.39.0")]
     pub fn saturating_duration_since(&self, earlier: Instant) -> Duration {
         self.checked_duration_since(earlier).unwrap_or(Duration::new(0, 0))
     }
diff --git a/src/tools/tidy/src/features/tests.rs b/src/tools/tidy/src/features/tests.rs
index fa7a931ec865c..994523ac1abce 100644
--- a/src/tools/tidy/src/features/tests.rs
+++ b/src/tools/tidy/src/features/tests.rs
@@ -2,8 +2,8 @@ use super::*;
 
 #[test]
 fn test_find_attr_val() {
-    let s = r#"#[unstable(feature = "checked_duration_since", issue = "58402")]"#;
-    assert_eq!(find_attr_val(s, "feature"), Some("checked_duration_since"));
+    let s = r#"#[unstable(feature = "tidy_test_never_used_anywhere_else", issue = "58402")]"#;
+    assert_eq!(find_attr_val(s, "feature"), Some("tidy_test_never_used_anywhere_else"));
     assert_eq!(find_attr_val(s, "issue"), Some("58402"));
     assert_eq!(find_attr_val(s, "since"), None);
 }