diff --git a/library/core/src/char/methods.rs b/library/core/src/char/methods.rs
index 9b56db47b5c72..3dcaab6a12beb 100644
--- a/library/core/src/char/methods.rs
+++ b/library/core/src/char/methods.rs
@@ -1279,7 +1279,7 @@ impl char {
     ///
     /// [`to_ascii_uppercase()`]: #method.to_ascii_uppercase
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
-    #[rustc_const_unstable(feature = "const_char_make_ascii", issue = "130698")]
+    #[rustc_const_unstable(feature = "const_make_ascii", issue = "130698")]
     #[inline]
     pub const fn make_ascii_uppercase(&mut self) {
         *self = self.to_ascii_uppercase();
@@ -1305,7 +1305,7 @@ impl char {
     ///
     /// [`to_ascii_lowercase()`]: #method.to_ascii_lowercase
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
-    #[rustc_const_unstable(feature = "const_char_make_ascii", issue = "130698")]
+    #[rustc_const_unstable(feature = "const_make_ascii", issue = "130698")]
     #[inline]
     pub const fn make_ascii_lowercase(&mut self) {
         *self = self.to_ascii_lowercase();
diff --git a/library/core/src/num/mod.rs b/library/core/src/num/mod.rs
index 19f5b79d26149..31e35015d2de1 100644
--- a/library/core/src/num/mod.rs
+++ b/library/core/src/num/mod.rs
@@ -624,8 +624,9 @@ impl u8 {
     ///
     /// [`to_ascii_uppercase`]: Self::to_ascii_uppercase
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
+    #[rustc_const_unstable(feature = "const_make_ascii", issue = "130698")]
     #[inline]
-    pub fn make_ascii_uppercase(&mut self) {
+    pub const fn make_ascii_uppercase(&mut self) {
         *self = self.to_ascii_uppercase();
     }
 
@@ -649,8 +650,9 @@ impl u8 {
     ///
     /// [`to_ascii_lowercase`]: Self::to_ascii_lowercase
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
+    #[rustc_const_unstable(feature = "const_make_ascii", issue = "130698")]
     #[inline]
-    pub fn make_ascii_lowercase(&mut self) {
+    pub const fn make_ascii_lowercase(&mut self) {
         *self = self.to_ascii_lowercase();
     }