diff --git a/crates/oxc_data_structures/Cargo.toml b/crates/oxc_data_structures/Cargo.toml
index 4c07418e518b2..a627f093965ca 100644
--- a/crates/oxc_data_structures/Cargo.toml
+++ b/crates/oxc_data_structures/Cargo.toml
@@ -29,6 +29,6 @@ default = []
 all = ["assert_unchecked", "code_buffer", "inline_string", "rope", "stack"]
 assert_unchecked = []
 code_buffer = ["assert_unchecked"]
-inline_string = []
+inline_string = ["assert_unchecked"]
 rope = ["dep:ropey"]
 stack = ["assert_unchecked"]
diff --git a/crates/oxc_data_structures/src/inline_string.rs b/crates/oxc_data_structures/src/inline_string.rs
index 1b08e823efcc9..a1745996fe194 100644
--- a/crates/oxc_data_structures/src/inline_string.rs
+++ b/crates/oxc_data_structures/src/inline_string.rs
@@ -5,6 +5,8 @@ use std::{
     ops::{Add, AddAssign, Deref},
 };
 
+use crate::assert_unchecked;
+
 /// Short inline string.
 ///
 /// `CAPACITY` determines the maximum length of the string.
@@ -26,6 +28,7 @@ use std::{
 /// * `FixedSizeString<7, u8>` = 8 bytes
 /// * `FixedSizeString<8, usize>` = 16 bytes (on 64-bit platforms)
 /// * `FixedSizeString<12, u32>` = 16 bytes
+#[derive(Clone, Copy)]
 #[repr(C)]
 pub struct InlineString<const CAPACITY: usize, Len: UnsignedInt> {
     bytes: [u8; CAPACITY],
@@ -118,9 +121,10 @@ impl<const CAPACITY: usize, Len: UnsignedInt> InlineString<CAPACITY, Len> {
     #[inline]
     pub fn as_str(&self) -> &str {
         // SAFETY: If safety conditions of `push_unchecked` have been upheld,
-        // slice cannot be out of bounds, and contents of that slice is a valid UTF-8 string
+        // `self.len <= CAPACITY`, and contents of slice of `bytes` is a valid UTF-8 string
         unsafe {
-            let slice = self.bytes.get_unchecked(..self.len.to_usize());
+            assert_unchecked!(self.len.to_usize() <= CAPACITY);
+            let slice = &self.bytes[..self.len.to_usize()];
             std::str::from_utf8_unchecked(slice)
         }
     }