diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0b5ed73..8b5a4c4 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -27,7 +27,7 @@ jobs:
           persist-credentials: false
 
       - name: install Rust
-        uses: actions-rust-lang/setup-rust-toolchain@v1.3.5
+        uses: actions-rust-lang/setup-rust-toolchain@v1.17.0
         with:
           toolchain: ${{ matrix.version }}
 
@@ -50,7 +50,7 @@ jobs:
           persist-credentials: false
 
       - name: install Rust
-        uses: actions-rust-lang/setup-rust-toolchain@v1.3.5
+        uses: actions-rust-lang/setup-rust-toolchain@v1.17.0
         with: { components: rustfmt, clippy }
 
       - name: format
@@ -71,7 +71,7 @@ jobs:
           persist-credentials: false
 
       - name: install Rust
-        uses: actions-rust-lang/setup-rust-toolchain@v1.3.5
+        uses: actions-rust-lang/setup-rust-toolchain@v1.17.0
         with: { toolchain: nightly }
 
       - name: install cargo-hack
diff --git a/Cargo.toml b/Cargo.toml
index e085f1e..e699a7e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,3 +18,7 @@ tinyvec = { version = "1.4", features = ["rustc_1_55"] }
 [features]
 default = []
 alloc = ["hashbrown"]
+
+[dev-dependencies]
+# Keep the MSRV test graph compatible with Rust 1.61.
+once_cell = "=1.19.0"
diff --git a/src/array_map/iterators.rs b/src/array_map/iterators.rs
index 6717d64..c9d2c0b 100644
--- a/src/array_map/iterators.rs
+++ b/src/array_map/iterators.rs
@@ -83,7 +83,6 @@ impl<K, V, const N: usize> Iterator for IntoIter<K, V, N> {
     }
 
     #[inline]
-    #[must_use]
     fn size_hint(&self) -> (usize, Option<usize>) {
         (0, self.inner.size_hint().1)
     }
diff --git a/src/array_map/mod.rs b/src/array_map/mod.rs
index d5f0b5a..9016c06 100644
--- a/src/array_map/mod.rs
+++ b/src/array_map/mod.rs
@@ -176,18 +176,14 @@ impl<K: PartialOrd, V, const N: usize> ArrayMap<K, V, N> {
     fn node_by_key(&self, key: &K) -> Option<&Node<K, V>> {
         let mut current = self.root();
         loop {
-            match current {
+            let val = current?;
+            let node = self.node_at(val).expect("Invalid node tree");
+            current = match node.kv.0.partial_cmp(key) {
                 None => return None,
-                Some(val) => {
-                    let node = self.node_at(val).expect("Invalid node tree");
-                    current = match node.kv.0.partial_cmp(key) {
-                        None => return None,
-                        Some(Ordering::Equal) => return Some(node),
-                        Some(Ordering::Less) => node.children[0],
-                        Some(Ordering::Greater) => node.children[1],
-                    };
-                }
-            }
+                Some(Ordering::Equal) => return Some(node),
+                Some(Ordering::Less) => node.children[0],
+                Some(Ordering::Greater) => node.children[1],
+            };
         }
     }
 
@@ -196,20 +192,16 @@ impl<K: PartialOrd, V, const N: usize> ArrayMap<K, V, N> {
     fn node_by_key_mut(&mut self, key: &K) -> Option<&mut Node<K, V>> {
         let mut current = self.root();
         loop {
-            match current {
+            let val = current?;
+            let node = self.node_at(val).expect("Invalid node tree");
+            current = match node.kv.0.partial_cmp(key) {
                 None => return None,
-                Some(val) => {
-                    let node = self.node_at(val).expect("Invalid node tree");
-                    current = match node.kv.0.partial_cmp(key) {
-                        None => return None,
-                        Some(Ordering::Equal) => {
-                            return Some(self.node_at_mut(val).expect("Invalid node tree"));
-                        }
-                        Some(Ordering::Less) => node.children[0],
-                        Some(Ordering::Greater) => node.children[1],
-                    };
+                Some(Ordering::Equal) => {
+                    return Some(self.node_at_mut(val).expect("Invalid node tree"));
                 }
-            }
+                Some(Ordering::Less) => node.children[0],
+                Some(Ordering::Greater) => node.children[1],
+            };
         }
     }
 
@@ -433,10 +425,7 @@ impl<K: PartialOrd, V, const N: usize> ArrayMap<K, V, N> {
         let mut last_relationship = ParentChildRelation::ChildIsRoot;
         let mut current: Option<usize> = self.root;
         loop {
-            let c = match current {
-                Some(c) => c,
-                None => return None,
-            };
+            let c = current?;
             let cmp_node = self.node_at(c).expect(ERR_MSG);
             match cmp_node.kv.0.partial_cmp(key) {
                 None => return None,
diff --git a/src/tiny_map.rs b/src/tiny_map.rs
index 8cacb1d..2375e91 100644
--- a/src/tiny_map.rs
+++ b/src/tiny_map.rs
@@ -216,6 +216,13 @@ impl<K: PartialOrd + Eq + Hash, V, const N: usize> TinyMap<K, V, N> {
     }
 }
 
+impl<K: PartialOrd + Eq + Hash, V, const N: usize> Default for TinyMap<K, V, N> {
+    #[inline]
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl<K: PartialOrd + Eq + Hash, V, const N: usize> IntoIterator for TinyMap<K, V, N> {
     type Item = (K, V);
     type IntoIter = IntoIter<K, V, N>;