diff --git a/src/liballoc/slice.rs b/src/liballoc/slice.rs
index ac815629dcfb3..18bb13d847a87 100644
--- a/src/liballoc/slice.rs
+++ b/src/liballoc/slice.rs
@@ -1630,7 +1630,7 @@ impl<T> [T] {
 #[cfg(not(test))]
 impl [u8] {
     /// Checks if all bytes in this slice are within the ASCII range.
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn is_ascii(&self) -> bool {
         self.iter().all(|b| b.is_ascii())
@@ -1645,7 +1645,7 @@ impl [u8] {
     /// To uppercase the value in-place, use [`make_ascii_uppercase`].
     ///
     /// [`make_ascii_uppercase`]: #method.make_ascii_uppercase
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn to_ascii_uppercase(&self) -> Vec<u8> {
         let mut me = self.to_vec();
@@ -1662,7 +1662,7 @@ impl [u8] {
     /// To lowercase the value in-place, use [`make_ascii_lowercase`].
     ///
     /// [`make_ascii_lowercase`]: #method.make_ascii_lowercase
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn to_ascii_lowercase(&self) -> Vec<u8> {
         let mut me = self.to_vec();
@@ -1674,7 +1674,7 @@ impl [u8] {
     ///
     /// Same as `to_ascii_lowercase(a) == to_ascii_lowercase(b)`,
     /// but without allocating and copying temporaries.
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn eq_ignore_ascii_case(&self, other: &[u8]) -> bool {
         self.len() == other.len() &&
@@ -1692,7 +1692,7 @@ impl [u8] {
     /// [`to_ascii_uppercase`].
     ///
     /// [`to_ascii_uppercase`]: #method.to_ascii_uppercase
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn make_ascii_uppercase(&mut self) {
         for byte in self {
@@ -1709,7 +1709,7 @@ impl [u8] {
     /// [`to_ascii_lowercase`].
     ///
     /// [`to_ascii_lowercase`]: #method.to_ascii_lowercase
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn make_ascii_lowercase(&mut self) {
         for byte in self {
diff --git a/src/liballoc/str.rs b/src/liballoc/str.rs
index 975ea4e1a3e01..7fa872f4ded57 100644
--- a/src/liballoc/str.rs
+++ b/src/liballoc/str.rs
@@ -2078,7 +2078,7 @@ impl str {
     /// assert!(ascii.is_ascii());
     /// assert!(!non_ascii.is_ascii());
     /// ```
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn is_ascii(&self) -> bool {
         // We can treat each byte as character here: all multibyte characters
@@ -2108,7 +2108,7 @@ impl str {
     ///
     /// [`make_ascii_uppercase`]: #method.make_ascii_uppercase
     /// [`to_uppercase`]: #method.to_uppercase
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn to_ascii_uppercase(&self) -> String {
         let mut bytes = self.as_bytes().to_vec();
@@ -2138,7 +2138,7 @@ impl str {
     ///
     /// [`make_ascii_lowercase`]: #method.make_ascii_lowercase
     /// [`to_lowercase`]: #method.to_lowercase
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn to_ascii_lowercase(&self) -> String {
         let mut bytes = self.as_bytes().to_vec();
@@ -2159,7 +2159,7 @@ impl str {
     /// assert!("Ferrös".eq_ignore_ascii_case("FERRöS"));
     /// assert!(!"Ferrös".eq_ignore_ascii_case("FERRÖS"));
     /// ```
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn eq_ignore_ascii_case(&self, other: &str) -> bool {
         self.as_bytes().eq_ignore_ascii_case(other.as_bytes())
@@ -2174,7 +2174,7 @@ impl str {
     /// [`to_ascii_uppercase`].
     ///
     /// [`to_ascii_uppercase`]: #method.to_ascii_uppercase
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     pub fn make_ascii_uppercase(&mut self) {
         let me = unsafe { self.as_bytes_mut() };
         me.make_ascii_uppercase()
@@ -2189,7 +2189,7 @@ impl str {
     /// [`to_ascii_lowercase`].
     ///
     /// [`to_ascii_lowercase`]: #method.to_ascii_lowercase
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     pub fn make_ascii_lowercase(&mut self) {
         let me = unsafe { self.as_bytes_mut() };
         me.make_ascii_lowercase()
diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index 5b9dd4b1c6999..0aad354a87299 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -2286,7 +2286,7 @@ impl u8 {
     /// assert!(ascii.is_ascii());
     /// assert!(!non_ascii.is_ascii());
     /// ```
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn is_ascii(&self) -> bool {
         *self & 128 == 0
@@ -2308,7 +2308,7 @@ impl u8 {
     /// ```
     ///
     /// [`make_ascii_uppercase`]: #method.make_ascii_uppercase
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn to_ascii_uppercase(&self) -> u8 {
         ASCII_UPPERCASE_MAP[*self as usize]
@@ -2330,7 +2330,7 @@ impl u8 {
     /// ```
     ///
     /// [`make_ascii_lowercase`]: #method.make_ascii_lowercase
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn to_ascii_lowercase(&self) -> u8 {
         ASCII_LOWERCASE_MAP[*self as usize]
@@ -2348,7 +2348,7 @@ impl u8 {
     ///
     /// assert!(lowercase_a.eq_ignore_ascii_case(&uppercase_a));
     /// ```
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn eq_ignore_ascii_case(&self, other: &u8) -> bool {
         self.to_ascii_lowercase() == other.to_ascii_lowercase()
@@ -2373,7 +2373,7 @@ impl u8 {
     /// ```
     ///
     /// [`to_ascii_uppercase`]: #method.to_ascii_uppercase
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn make_ascii_uppercase(&mut self) {
         *self = self.to_ascii_uppercase();
@@ -2398,7 +2398,7 @@ impl u8 {
     /// ```
     ///
     /// [`to_ascii_lowercase`]: #method.to_ascii_lowercase
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn make_ascii_lowercase(&mut self) {
         *self = self.to_ascii_lowercase();
diff --git a/src/libstd_unicode/char.rs b/src/libstd_unicode/char.rs
index 6b573e5011bfa..ef11fb694ab01 100644
--- a/src/libstd_unicode/char.rs
+++ b/src/libstd_unicode/char.rs
@@ -938,7 +938,7 @@ impl char {
     /// assert!(ascii.is_ascii());
     /// assert!(!non_ascii.is_ascii());
     /// ```
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn is_ascii(&self) -> bool {
         *self as u32 <= 0x7F
@@ -966,7 +966,7 @@ impl char {
     ///
     /// [`make_ascii_uppercase`]: #method.make_ascii_uppercase
     /// [`to_uppercase`]: #method.to_uppercase
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn to_ascii_uppercase(&self) -> char {
         if self.is_ascii() {
@@ -998,7 +998,7 @@ impl char {
     ///
     /// [`make_ascii_lowercase`]: #method.make_ascii_lowercase
     /// [`to_lowercase`]: #method.to_lowercase
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn to_ascii_lowercase(&self) -> char {
         if self.is_ascii() {
@@ -1023,7 +1023,7 @@ impl char {
     /// assert!(upper_a.eq_ignore_ascii_case(&upper_a));
     /// assert!(!upper_a.eq_ignore_ascii_case(&lower_z));
     /// ```
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn eq_ignore_ascii_case(&self, other: &char) -> bool {
         self.to_ascii_lowercase() == other.to_ascii_lowercase()
@@ -1048,7 +1048,7 @@ impl char {
     /// ```
     ///
     /// [`to_ascii_uppercase`]: #method.to_ascii_uppercase
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn make_ascii_uppercase(&mut self) {
         *self = self.to_ascii_uppercase();
@@ -1073,7 +1073,7 @@ impl char {
     /// ```
     ///
     /// [`to_ascii_lowercase`]: #method.to_ascii_lowercase
-    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.21.0")]
+    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn make_ascii_lowercase(&mut self) {
         *self = self.to_ascii_lowercase();