diff --git a/library/core/src/char/methods.rs b/library/core/src/char/methods.rs
index 9d9a3b5132cf9..2a0acfeacdf75 100644
--- a/library/core/src/char/methods.rs
+++ b/library/core/src/char/methods.rs
@@ -1277,7 +1277,7 @@ 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();
@@ -1303,7 +1303,7 @@ 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 dca644ebef4ad..1f6e43bdba3e6 100644
--- a/library/core/src/num/mod.rs
+++ b/library/core/src/num/mod.rs
@@ -614,8 +614,9 @@ 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();
     }
 
@@ -639,8 +640,9 @@ 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();
     }