diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index a4134143..e07624a0 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -16,7 +16,7 @@ jobs:
         uses: actions/checkout@master
       - uses: actions-rs/toolchain@v1
         with:
-            toolchain: 1.69.0
+            toolchain: 1.80.0
             default: true
             components: rustfmt, clippy
       - name: Check Rust formatting
diff --git a/src/lib.rs b/src/lib.rs
index 81fa1413..dbb9e34f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -592,7 +592,7 @@ where
     }
 
     /// Write out the shard positioning data
-    fn write_index(&mut self) -> Result<(), Error> {
+    pub fn write_index(&mut self) -> Result<(), Error> {
         let mut buf = Vec::new();
 
         serialize_into(&mut buf, &(type_name::<T>(), type_name::<S>()))?;
@@ -1549,7 +1549,6 @@ mod shard_tests {
     use std::fmt::Debug;
     use std::hash::Hash;
     use std::iter::{repeat, FromIterator};
-    use std::u8;
 
     #[derive(Copy, Clone, Eq, PartialEq, Serialize, Deserialize, Debug, PartialOrd, Ord, Hash)]
     struct T1 {
@@ -2065,7 +2064,7 @@ mod shard_tests {
                     chunks.len() <= 256,
                     "chunks > |T1.d| ({} > {})",
                     chunks.len(),
-                    u8::max_value()
+                    u8::MAX
                 );
                 for c in chunks {
                     let itr = set_reader.iter_range(&c)?;