diff --git a/Cargo.lock b/Cargo.lock
index 23b01f23c50ea..12de551fcb4e4 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3672,6 +3672,7 @@ name = "rustc_ast"
 version = "0.0.0"
 dependencies = [
  "bitflags",
+ "memchr",
  "rustc_data_structures",
  "rustc_index",
  "rustc_lexer",
diff --git a/compiler/rustc_ast/Cargo.toml b/compiler/rustc_ast/Cargo.toml
index 9253b7e6891a2..10d7fa1db605a 100644
--- a/compiler/rustc_ast/Cargo.toml
+++ b/compiler/rustc_ast/Cargo.toml
@@ -7,6 +7,7 @@ edition = "2021"
 
 [dependencies]
 bitflags = "1.2.1"
+memchr = "2.5.0"
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_index = { path = "../rustc_index" }
 rustc_lexer = { path = "../rustc_lexer" }
diff --git a/compiler/rustc_ast/src/lib.rs b/compiler/rustc_ast/src/lib.rs
index 0f8ebcfdc1508..23c32fa96ca44 100644
--- a/compiler/rustc_ast/src/lib.rs
+++ b/compiler/rustc_ast/src/lib.rs
@@ -16,7 +16,6 @@
 #![feature(let_chains)]
 #![feature(min_specialization)]
 #![feature(negative_impls)]
-#![feature(slice_internals)]
 #![feature(stmt_expr_attributes)]
 #![recursion_limit = "256"]
 #![deny(rustc::untranslatable_diagnostic)]
diff --git a/compiler/rustc_ast/src/util/unicode.rs b/compiler/rustc_ast/src/util/unicode.rs
index 0eae791b25e1c..6f57d66b2273a 100644
--- a/compiler/rustc_ast/src/util/unicode.rs
+++ b/compiler/rustc_ast/src/util/unicode.rs
@@ -17,7 +17,7 @@ pub fn contains_text_flow_control_chars(s: &str) -> bool {
     // U+2069 - E2 81 A9
     let mut bytes = s.as_bytes();
     loop {
-        match core::slice::memchr::memchr(0xE2, bytes) {
+        match memchr::memchr(0xE2, bytes) {
             Some(idx) => {
                 // bytes are valid UTF-8 -> E2 must be followed by two bytes
                 let ch = &bytes[idx..idx + 3];