diff --git a/src/history/file.rs b/src/history/file.rs
index 50ad3c4d3..6127a42df 100644
--- a/src/history/file.rs
+++ b/src/history/file.rs
@@ -270,15 +270,13 @@ fn maybe_unescape_yaml_fish_2_0(s: &[u8]) -> Cow<[u8]> {
 //
 // Benchmarks and code: https://github.com/mqudsi/fish-yaml-unescape-benchmark
 fn unescape_yaml_fish_2_0(s: &[u8]) -> Vec<u8> {
-    // Safety: we never read from this box; we only write to it then read what we've written.
-    // Rationale: This function is in a very hot loop and this benchmarks around 8% faster on
-    // real-world escaped yaml samples from the fish history file.
-    //
+    // This function is in a very hot loop and the usage of boxed uninit memory benchmarks around 8%
+    // faster on real-world escaped yaml samples from the fish history file.
+
     // This is a very long way around of writing `Box::new_uninit_slice(s.len())`, which
     // requires the unstablized nightly-only feature new_unit (#63291). It optimizes away.
-    let mut result: Box<[u8]> = std::iter::repeat_with(std::mem::MaybeUninit::uninit)
+    let mut result: Box<[_]> = std::iter::repeat_with(std::mem::MaybeUninit::uninit)
         .take(s.len())
-        .map(|b| unsafe { b.assume_init() })
         .collect();
     let mut chars = s.iter().copied();
     let mut src_idx = 0;
@@ -289,21 +287,26 @@ fn unescape_yaml_fish_2_0(s: &[u8]) -> Vec<u8> {
         // everywhere does not result in a statistically significant improvement to the
         // performance of this function.
         let to_copy = chars.by_ref().take_while(|b| *b != b'\\').count();
-        result[dst_idx..][..to_copy].copy_from_slice(&s[src_idx..][..to_copy]);
+        unsafe {
+            let src = &s[src_idx..].as_ptr();
+            // Can use the following when feature(maybe_uninit_slice) is stabilized:
+            // let dst = std::mem::MaybeUninit::slice_as_mut_ptr(&mut result[dst_idx..]);
+            let dst = result[dst_idx..].as_mut_ptr().cast();
+            std::ptr::copy_nonoverlapping(*src, dst, to_copy);
+        }
         dst_idx += to_copy;
 
         match chars.next() {
-            Some(b'\\') => result[dst_idx] = b'\\',
-            Some(b'n') => result[dst_idx] = b'\n',
+            Some(b'\\') => result[dst_idx].write(b'\\'),
+            Some(b'n') => result[dst_idx].write(b'\n'),
             _ => break,
-        }
+        };
         src_idx += to_copy + 2;
         dst_idx += 1;
     }
 
-    let mut result = Vec::from(result);
-    result.truncate(dst_idx);
-    result
+    let result = Box::leak(result);
+    unsafe { Vec::from_raw_parts(result.as_mut_ptr().cast(), dst_idx, result.len()) }
 }
 
 /// Read one line, stripping off any newline, returning the number of bytes consumed.