diff --git a/src/libcore/char/methods.rs b/src/libcore/char/methods.rs
index c341bb552a1ea..2b52c48cb9077 100644
--- a/src/libcore/char/methods.rs
+++ b/src/libcore/char/methods.rs
@@ -1072,8 +1072,9 @@ impl char {
     /// assert!(!esc.is_ascii_alphabetic());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_alphabetic(&self) -> bool {
+    pub const fn is_ascii_alphabetic(&self) -> bool {
         self.is_ascii() && (*self as u8).is_ascii_alphabetic()
     }
 
@@ -1104,8 +1105,9 @@ impl char {
     /// assert!(!esc.is_ascii_uppercase());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_uppercase(&self) -> bool {
+    pub const fn is_ascii_uppercase(&self) -> bool {
         self.is_ascii() && (*self as u8).is_ascii_uppercase()
     }
 
@@ -1136,8 +1138,9 @@ impl char {
     /// assert!(!esc.is_ascii_lowercase());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_lowercase(&self) -> bool {
+    pub const fn is_ascii_lowercase(&self) -> bool {
         self.is_ascii() && (*self as u8).is_ascii_lowercase()
     }
 
@@ -1171,8 +1174,9 @@ impl char {
     /// assert!(!esc.is_ascii_alphanumeric());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_alphanumeric(&self) -> bool {
+    pub const fn is_ascii_alphanumeric(&self) -> bool {
         self.is_ascii() && (*self as u8).is_ascii_alphanumeric()
     }
 
@@ -1203,8 +1207,9 @@ impl char {
     /// assert!(!esc.is_ascii_digit());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_digit(&self) -> bool {
+    pub const fn is_ascii_digit(&self) -> bool {
         self.is_ascii() && (*self as u8).is_ascii_digit()
     }
 
@@ -1238,8 +1243,9 @@ impl char {
     /// assert!(!esc.is_ascii_hexdigit());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_hexdigit(&self) -> bool {
+    pub const fn is_ascii_hexdigit(&self) -> bool {
         self.is_ascii() && (*self as u8).is_ascii_hexdigit()
     }
 
@@ -1274,8 +1280,9 @@ impl char {
     /// assert!(!esc.is_ascii_punctuation());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_punctuation(&self) -> bool {
+    pub const fn is_ascii_punctuation(&self) -> bool {
         self.is_ascii() && (*self as u8).is_ascii_punctuation()
     }
 
@@ -1306,8 +1313,9 @@ impl char {
     /// assert!(!esc.is_ascii_graphic());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_graphic(&self) -> bool {
+    pub const fn is_ascii_graphic(&self) -> bool {
         self.is_ascii() && (*self as u8).is_ascii_graphic()
     }
 
@@ -1355,8 +1363,9 @@ impl char {
     /// assert!(!esc.is_ascii_whitespace());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_whitespace(&self) -> bool {
+    pub const fn is_ascii_whitespace(&self) -> bool {
         self.is_ascii() && (*self as u8).is_ascii_whitespace()
     }
 
@@ -1389,8 +1398,9 @@ impl char {
     /// assert!(esc.is_ascii_control());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_control(&self) -> bool {
+    pub const fn is_ascii_control(&self) -> bool {
         self.is_ascii() && (*self as u8).is_ascii_control()
     }
 }
diff --git a/src/libcore/lib.rs b/src/libcore/lib.rs
index 1fd70e1a1b049..176c36664a9b1 100644
--- a/src/libcore/lib.rs
+++ b/src/libcore/lib.rs
@@ -70,6 +70,7 @@
 #![feature(bound_cloned)]
 #![feature(cfg_target_has_atomic)]
 #![feature(concat_idents)]
+#![feature(const_ascii_ctype_on_intrinsics)]
 #![feature(const_alloc_layout)]
 #![feature(const_if_match)]
 #![feature(const_checked_int_methods)]
diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index 3ae8f0f7870c1..471ab96662249 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -4449,8 +4449,9 @@ impl u8 {
     /// assert!(!esc.is_ascii_alphabetic());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_alphabetic(&self) -> bool {
+    pub const fn is_ascii_alphabetic(&self) -> bool {
         matches!(*self, b'A'..=b'Z' | b'a'..=b'z')
     }
 
@@ -4481,8 +4482,9 @@ impl u8 {
     /// assert!(!esc.is_ascii_uppercase());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_uppercase(&self) -> bool {
+    pub const fn is_ascii_uppercase(&self) -> bool {
         matches!(*self, b'A'..=b'Z')
     }
 
@@ -4513,8 +4515,9 @@ impl u8 {
     /// assert!(!esc.is_ascii_lowercase());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_lowercase(&self) -> bool {
+    pub const fn is_ascii_lowercase(&self) -> bool {
         matches!(*self, b'a'..=b'z')
     }
 
@@ -4548,8 +4551,9 @@ impl u8 {
     /// assert!(!esc.is_ascii_alphanumeric());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_alphanumeric(&self) -> bool {
+    pub const fn is_ascii_alphanumeric(&self) -> bool {
         matches!(*self, b'0'..=b'9' | b'A'..=b'Z' | b'a'..=b'z')
     }
 
@@ -4580,8 +4584,9 @@ impl u8 {
     /// assert!(!esc.is_ascii_digit());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_digit(&self) -> bool {
+    pub const fn is_ascii_digit(&self) -> bool {
         matches!(*self, b'0'..=b'9')
     }
 
@@ -4615,8 +4620,9 @@ impl u8 {
     /// assert!(!esc.is_ascii_hexdigit());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_hexdigit(&self) -> bool {
+    pub const fn is_ascii_hexdigit(&self) -> bool {
         matches!(*self, b'0'..=b'9' | b'A'..=b'F' | b'a'..=b'f')
     }
 
@@ -4651,8 +4657,9 @@ impl u8 {
     /// assert!(!esc.is_ascii_punctuation());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_punctuation(&self) -> bool {
+    pub const fn is_ascii_punctuation(&self) -> bool {
         matches!(*self, b'!'..=b'/' | b':'..=b'@' | b'['..=b'`' | b'{'..=b'~')
     }
 
@@ -4683,8 +4690,9 @@ impl u8 {
     /// assert!(!esc.is_ascii_graphic());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_graphic(&self) -> bool {
+    pub const fn is_ascii_graphic(&self) -> bool {
         matches!(*self, b'!'..=b'~')
     }
 
@@ -4732,8 +4740,9 @@ impl u8 {
     /// assert!(!esc.is_ascii_whitespace());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_whitespace(&self) -> bool {
+    pub const fn is_ascii_whitespace(&self) -> bool {
         matches!(*self, b'\t' | b'\n' | b'\x0C' | b'\r' | b' ')
     }
 
@@ -4766,8 +4775,9 @@ impl u8 {
     /// assert!(esc.is_ascii_control());
     /// ```
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
+    #[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
     #[inline]
-    pub fn is_ascii_control(&self) -> bool {
+    pub const fn is_ascii_control(&self) -> bool {
         matches!(*self, b'\0'..=b'\x1F' | b'\x7F')
     }
 }
diff --git a/src/test/ui/consts/ascii_ctype.rs b/src/test/ui/consts/ascii_ctype.rs
new file mode 100644
index 0000000000000..25b270ee49cae
--- /dev/null
+++ b/src/test/ui/consts/ascii_ctype.rs
@@ -0,0 +1,55 @@
+// run-pass
+
+#![feature(const_ascii_ctype_on_intrinsics)]
+
+macro_rules! suite {
+    ( $( $fn:ident => [$a:ident, $A:ident, $nine:ident, $dot:ident, $space:ident]; )* ) => {
+        $(
+            mod $fn {
+                const CHAR_A_LOWER: bool = 'a'.$fn();
+                const CHAR_A_UPPER: bool = 'A'.$fn();
+                const CHAR_NINE: bool = '9'.$fn();
+                const CHAR_DOT: bool = '.'.$fn();
+                const CHAR_SPACE: bool = ' '.$fn();
+
+                const U8_A_LOWER: bool = b'a'.$fn();
+                const U8_A_UPPER: bool = b'A'.$fn();
+                const U8_NINE: bool = b'9'.$fn();
+                const U8_DOT: bool = b'.'.$fn();
+                const U8_SPACE: bool = b' '.$fn();
+
+                pub fn run() {
+                    assert_eq!(CHAR_A_LOWER, $a);
+                    assert_eq!(CHAR_A_UPPER, $A);
+                    assert_eq!(CHAR_NINE, $nine);
+                    assert_eq!(CHAR_DOT, $dot);
+                    assert_eq!(CHAR_SPACE, $space);
+
+                    assert_eq!(U8_A_LOWER, $a);
+                    assert_eq!(U8_A_UPPER, $A);
+                    assert_eq!(U8_NINE, $nine);
+                    assert_eq!(U8_DOT, $dot);
+                    assert_eq!(U8_SPACE, $space);
+                }
+            }
+        )*
+
+        fn main() {
+            $( $fn::run(); )*
+        }
+    }
+}
+
+suite! {
+    //                        'a'    'A'    '9'    '.'    ' '
+    is_ascii_alphabetic   => [true,  true,  false, false, false];
+    is_ascii_uppercase    => [false, true,  false, false, false];
+    is_ascii_lowercase    => [true,  false, false, false, false];
+    is_ascii_alphanumeric => [true,  true,  true,  false, false];
+    is_ascii_digit        => [false, false, true,  false, false];
+    is_ascii_hexdigit     => [true,  true,  true,  false, false];
+    is_ascii_punctuation  => [false, false, false, true,  false];
+    is_ascii_graphic      => [true,  true,  true,  true,  false];
+    is_ascii_whitespace   => [false, false, false, false, true];
+    is_ascii_control      => [false, false, false, false, false];
+}