diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 213ef14..8099e67 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -6,49 +6,42 @@ on:
 
 name: CI
 
+# Adapted from recipe: https://github.com/actions-rs/meta/blob/master/recipes/matrix.md#workflow.
 jobs:
   ci:
-    runs-on: [ubuntu-latest, windows-latest, macOS-latest]
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        rust:
+          - stable
+          - beta
+          - nightly
+          - 1.56.0  # MSRV
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v2
 
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal
-          toolchain: stable
+          toolchain: ${{ matrix.rust }}
+          override: true
           components: rustfmt, clippy
 
       - uses: actions-rs/cargo@v1
         with:
-          command: fmt
-          args: --all -- --check
-
-      - uses: actions-rs/install@v0.1
-        with:
-          crate: cargo-hack
-          version: latest
-          use-tool-cache: true
+          command: build
 
       - uses: actions-rs/cargo@v1
         with:
-          command: hack
-          args: check --workspace --ignore-private --each-feature --no-dev-deps
+          command: test
 
       - uses: actions-rs/cargo@v1
         with:
-          command: check
-          args: --workspace --all-targets --all-features
+          command: fmt
+          args: --all -- --check
 
       - uses: actions-rs/cargo@v1
         with:
-          command: test
-
-      - uses: actions-rs/clippy-check@v1
-        with:
-          token: ${{ secrets.GITHUB_TOKEN }}
-          args: --all-features
-
-      - uses: actions-rs/audit-check@v1
-        with:
-          token: ${{ secrets.GITHUB_TOKEN }}
+          command: clippy
+          args: -- -D warnings
diff --git a/README.md b/README.md
index 3f33cec..cf1855e 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ An implementation of a LRU cache. The cache supports `put`, `get`, `get_mut` and
 all of which are O(1). This crate was heavily influenced by the [LRU Cache implementation in an
 earlier version of Rust's std::collections crate].
 
-The MSRV for this crate is 1.36.0.
+The MSRV for this crate is 1.56.0.
 
 ## Example
 
diff --git a/src/lib.rs b/src/lib.rs
index f002a88..7f09dbe 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -356,6 +356,7 @@ impl<K: Hash + Eq, V, S: BuildHasher> LruCache<K, V, S> {
 
     // Used internally to swap out a node if the cache is full or to create a new node if space
     // is available. Shared between `put`, `push`, and `get_or_insert`.
+    #[allow(clippy::type_complexity)]
     fn replace_or_create_node(&mut self, k: K, v: V) -> (Option<(K, V)>, Box<LruEntry<K, V>>) {
         if self.len() == self.cap() {
             // if the cache is full, remove the last entry so we can use it for the new key
@@ -474,7 +475,7 @@ impl<K: Hash + Eq, V, S: BuildHasher> LruCache<K, V, S> {
     /// assert_eq!(cache.get_or_insert(1, ||"a"), Some(&"a"));
     /// assert_eq!(cache.get_or_insert(1, ||"b"), Some(&"a"));
     /// ```
-    pub fn get_or_insert<'a, F>(&'a mut self, k: K, f: F) -> Option<&'a V>
+    pub fn get_or_insert<'a, F>(&mut self, k: K, f: F) -> Option<&'a V>
     where
         F: FnOnce() -> V,
     {
@@ -526,7 +527,7 @@ impl<K: Hash + Eq, V, S: BuildHasher> LruCache<K, V, S> {
     {
         self.map
             .get(k)
-            .map(|node| unsafe { &(*(*node).val.as_ptr()) as &V })
+            .map(|node| unsafe { &(*node.val.as_ptr()) as &V })
     }
 
     /// Returns a mutable reference to the value corresponding to the key in the cache or `None`
@@ -552,7 +553,7 @@ impl<K: Hash + Eq, V, S: BuildHasher> LruCache<K, V, S> {
     {
         match self.map.get_mut(k) {
             None => None,
-            Some(node) => Some(unsafe { &mut (*(*node).val.as_mut_ptr()) as &mut V }),
+            Some(node) => Some(unsafe { &mut (*node.val.as_mut_ptr()) as &mut V }),
         }
     }
 
@@ -915,10 +916,9 @@ impl<K, V, S> Drop for LruCache<K, V, S> {
         });
         // We rebox the head/tail, and because these are maybe-uninit
         // they do not have the absent k/v dropped.
-        
-            let _head = unsafe { *Box::from_raw(self.head) };
-            let _tail = unsafe { *Box::from_raw(self.tail) };
-        
+
+        let _head = unsafe { *Box::from_raw(self.head) };
+        let _tail = unsafe { *Box::from_raw(self.tail) };
     }
 }