diff --git a/crates/samlang-heap/src/lib.rs b/crates/samlang-heap/src/lib.rs
index 8371b181..a46e23b1 100644
--- a/crates/samlang-heap/src/lib.rs
+++ b/crates/samlang-heap/src/lib.rs
@@ -309,7 +309,7 @@ impl ModuleReference {
   }
 
   pub fn is_std(&self, heap: &Heap) -> bool {
-    self.get_parts(heap).get(0) == Some(&PStr::STD)
+    self.get_parts(heap).first() == Some(&PStr::STD)
   }
 
   pub fn pretty_print(&self, heap: &Heap) -> String {
diff --git a/crates/samlang-optimization/src/loop_induction_analysis.rs b/crates/samlang-optimization/src/loop_induction_analysis.rs
index a30fd91f..8d1b7a5c 100644
--- a/crates/samlang-optimization/src/loop_induction_analysis.rs
+++ b/crates/samlang-optimization/src/loop_induction_analysis.rs
@@ -423,7 +423,7 @@ fn extract_loop_guard_structure(
   non_loop_invariant_variables: &HashSet<PStr>,
 ) -> Option<LoopGuardStructure> {
   let (first_binary_stmt, second_single_if_stmt) =
-    (stmts.get(0).and_then(Statement::as_binary), stmts.get(1).and_then(Statement::as_single_if));
+    (stmts.first().and_then(Statement::as_binary), stmts.get(1).and_then(Statement::as_single_if));
   match (first_binary_stmt, second_single_if_stmt) {
     (
       Some(Binary { name, operator, e1: Expression::Variable(e1_var), e2 }),