diff --git a/Cargo.toml b/Cargo.toml
index 634dc23..7ca15fd 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -17,13 +17,30 @@ license = "MIT"
 
 [lints.clippy]
 all = "deny"
-suspicious = "deny"
-style = "deny"
+clone_on_ref_ptr = "deny"
 complexity = "deny"
-perf = "deny"
-must_use_candidate = "deny"
+dbg_macro = "deny"
 doc_markdown = "deny"
+exhaustive_structs = "deny"
+indexing_slicing = "deny"
+let_underscore_must_use = "deny"
+map_err_ignore = "deny"
 missing_const_for_fn = "deny"
+must_use_candidate = "deny"
+perf = "deny"
+print_stderr = "deny"
+print_stdout = "deny"
+rc_buffer = "deny"
+rc_mutex = "deny"
+redundant_type_annotations = "deny"
+string_to_string = "deny"
+style = "deny"
+suspicious = "deny"
+tests_outside_test_module = "deny"
+todo = "deny"
+try_err = "deny"
+undocumented_unsafe_blocks = "deny"
+use_debug = "deny"
 
 [dependencies]
 tracing = { version = "0.1.37", optional = true }
diff --git a/benches/criterion.rs b/benches/criterion.rs
index 6543877..e7cbce0 100644
--- a/benches/criterion.rs
+++ b/benches/criterion.rs
@@ -36,7 +36,8 @@ fn examples(c: &mut Criterion) {
     c.bench_function("parse polish calculator", |b| {
         b.iter(|| {
             let input = random_walks.choose(&mut rng).unwrap();
-            let _: Vec<_> = polish_calc_grammar.parse_input(input).collect();
+            let parses: Vec<_> = polish_calc_grammar.parse_input(input).collect();
+            assert!(!parses.is_empty());
         })
     });
 
@@ -55,10 +56,11 @@ fn examples(c: &mut Criterion) {
             &parse_count,
             |b, &parse_count| {
                 b.iter(|| {
-                    let _: Vec<_> = infinite_grammar
+                    let parses: Vec<_> = infinite_grammar
                         .parse_input(input)
                         .take(parse_count)
                         .collect();
+                    assert_eq!(parses.len(), parse_count);
                 })
             },
         );
diff --git a/benches/divan.rs b/benches/divan.rs
index ab6c48e..37729ce 100644
--- a/benches/divan.rs
+++ b/benches/divan.rs
@@ -61,7 +61,7 @@ mod examples {
 
         bencher.bench_local(|| {
             let index = index.next().unwrap();
-            let input = &random_walks[index];
+            let input = random_walks.get(index).unwrap();
             polish_calc_grammar
                 .parse_input(input)
                 .for_each(divan::black_box_drop);
diff --git a/src/earley/input_range.rs b/src/earley/input_range.rs
index 58be2f5..243ebf6 100644
--- a/src/earley/input_range.rs
+++ b/src/earley/input_range.rs
@@ -26,7 +26,7 @@ impl<'gram> InputRange<'gram> {
     }
     pub fn next(&self) -> &'gram str {
         let next_idx = self.offset.start + self.offset.len;
-        &self.input[next_idx..]
+        self.input.get(next_idx..).unwrap_or("")
     }
     pub const fn after(&self) -> Self {
         Self {
@@ -56,9 +56,13 @@ impl<'gram> InputRange<'gram> {
 impl<'gram> std::fmt::Debug for InputRange<'gram> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         let InputRangeOffset { start, len, .. } = self.offset;
-        let before = &self.input[..start];
-        let scanned = &self.input[start..][..len];
-        let after = &self.input[start..][len..];
+        let before = self.input.get(..start).unwrap_or("");
+        let scanned = self
+            .input
+            .get(start..)
+            .and_then(|s| s.get(..len))
+            .unwrap_or("");
+        let after = self.input.get(start + len..).unwrap_or("");
         write!(f, "InputRange(\"{before}|{scanned}|{after}\")",)
     }
 }
diff --git a/src/earley/mod.rs b/src/earley/mod.rs
index e077ee4..1e5e5bf 100644
--- a/src/earley/mod.rs
+++ b/src/earley/mod.rs
@@ -288,7 +288,8 @@ mod tests {
 
             let expr_indexes: Vec<usize> = (0..expressions.len()).collect();
             let expr_choice_index = g.choose(&expr_indexes).unwrap();
-            let expr_choice: &mut crate::Expression = expressions[*expr_choice_index];
+            let expr_choice: &mut crate::Expression =
+                expressions.get_mut(*expr_choice_index).unwrap();
 
             let term_choice_indexes: Vec<usize> = (0..expr_choice.terms.len()).collect();
             let term_choice_index = g.choose(&term_choice_indexes).unwrap();
diff --git a/src/earley/traversal.rs b/src/earley/traversal.rs
index adfa515..0c491a0 100644
--- a/src/earley/traversal.rs
+++ b/src/earley/traversal.rs
@@ -222,7 +222,10 @@ impl<'gram> TraversalTree<'gram> {
 
             let parent_id = parent.id;
             let production_id = parent.production_id;
-            let unmatched = &parent.unmatched[1..];
+            let unmatched = parent
+                .unmatched
+                .get(1..)
+                .expect("parent traversal has at least one unmatched term");
             let is_starting = parent.is_starting;
             let from = TraversalEdge { term, parent_id };
 
@@ -306,7 +309,7 @@ mod tests {
 
         let scanned = tree.match_term(prediction, term_match);
 
-        assert_eq!(scanned.unmatched, &production.rhs.terms[1..]);
+        assert_eq!(scanned.unmatched, production.rhs.terms.get(1..).unwrap());
     }
 
     #[test]
diff --git a/src/error.rs b/src/error.rs
index fd657a3..807d360 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -86,14 +86,17 @@ mod tests {
     #[test]
     fn from_nom_verbose_error() {
         let error = nom::error::VerboseError { errors: vec![] };
-        let _ = Error::from(error);
+        assert!(matches!(Error::from(error), Error::ParseError(_)));
     }
 
     #[test]
     fn from_str_and_nom_verbose_error_kind() {
         let description = "anything";
         let verbose_kind = nom::error::VerboseErrorKind::Char('z');
-        let _ = Error::from((description, verbose_kind));
+        assert!(matches!(
+            Error::from((description, verbose_kind)),
+            Error::ParseError(_)
+        ));
     }
 
     #[test]
diff --git a/src/expression.rs b/src/expression.rs
index ad7556c..762cc4b 100644
--- a/src/expression.rs
+++ b/src/expression.rs
@@ -195,13 +195,13 @@ mod tests {
 
     #[test]
     fn new_expressions() {
-        let t1: Term = Term::Terminal(String::from("terminal"));
-        let nt1: Term = Term::Nonterminal(String::from("nonterminal"));
-        let t2: Term = Term::Terminal(String::from("terminal"));
-        let nt2: Term = Term::Nonterminal(String::from("nonterminal"));
+        let t1 = Term::Terminal(String::from("terminal"));
+        let nt1 = Term::Nonterminal(String::from("nonterminal"));
+        let t2 = Term::Terminal(String::from("terminal"));
+        let nt2 = Term::Nonterminal(String::from("nonterminal"));
 
-        let e1: Expression = Expression::from_parts(vec![nt1, t1]);
-        let mut e2: Expression = Expression::new();
+        let e1 = Expression::from_parts(vec![nt1, t1]);
+        let mut e2 = Expression::new();
         e2.add_term(nt2);
         e2.add_term(t2);
 
diff --git a/src/grammar.rs b/src/grammar.rs
index e60a8ea..2239ff9 100644
--- a/src/grammar.rs
+++ b/src/grammar.rs
@@ -539,24 +539,24 @@ mod tests {
 
     #[test]
     fn new_grammars() {
-        let lhs1: Term = Term::Nonterminal(String::from("STRING A"));
-        let rhs1: Expression = Expression::from_parts(vec![
+        let lhs1 = Term::Nonterminal(String::from("STRING A"));
+        let rhs1 = Expression::from_parts(vec![
             Term::Terminal(String::from("STRING B")),
             Term::Nonterminal(String::from("STRING C")),
         ]);
-        let p1: Production = Production::from_parts(lhs1, vec![rhs1]);
+        let p1 = Production::from_parts(lhs1, vec![rhs1]);
 
-        let lhs2: Term = Term::Nonterminal(String::from("STRING A"));
-        let rhs2: Expression = Expression::from_parts(vec![
+        let lhs2 = Term::Nonterminal(String::from("STRING A"));
+        let rhs2 = Expression::from_parts(vec![
             Term::Terminal(String::from("STRING B")),
             Term::Nonterminal(String::from("STRING C")),
         ]);
-        let p2: Production = Production::from_parts(lhs2, vec![rhs2]);
+        let p2 = Production::from_parts(lhs2, vec![rhs2]);
 
-        let mut g1: Grammar = Grammar::new();
+        let mut g1 = Grammar::new();
         g1.add_production(p1.clone());
         g1.add_production(p2.clone());
-        let g2: Grammar = Grammar::from_parts(vec![p1, p2]);
+        let g2 = Grammar::from_parts(vec![p1, p2]);
         assert_eq!(g1, g2);
     }
 
@@ -722,7 +722,7 @@ mod tests {
 
         let rhs_iterated = parse_tree.rhs_iter().next().unwrap();
 
-        assert_eq!(&parse_tree.rhs[0], rhs_iterated);
+        assert_eq!(parse_tree.rhs.first().unwrap(), rhs_iterated);
     }
 
     #[test]
@@ -740,14 +740,15 @@ mod tests {
 
         *rhs_iterated = ParseTreeNode::Terminal("Z");
 
-        assert_eq!(parse_tree.rhs[0], ParseTreeNode::Terminal("Z"));
+        assert_eq!(
+            parse_tree.rhs.first().unwrap(),
+            &ParseTreeNode::Terminal("Z")
+        );
     }
 
     #[test]
     fn does_not_terminate() {
-        let mut grammar: Grammar;
-
-        grammar = "<nonterm> ::= <nonterm>".parse().unwrap();
+        let mut grammar: Grammar = "<nonterm> ::= <nonterm>".parse().unwrap();
         assert!(!grammar.terminates());
 
         grammar = "
diff --git a/src/production.rs b/src/production.rs
index fe35272..4cc897d 100644
--- a/src/production.rs
+++ b/src/production.rs
@@ -154,19 +154,19 @@ mod tests {
 
     #[test]
     fn new_productions() {
-        let lhs1: Term = Term::Nonterminal(String::from("STRING A"));
-        let rhs1: Expression = Expression::from_parts(vec![
+        let lhs1 = Term::Nonterminal(String::from("STRING A"));
+        let rhs1 = Expression::from_parts(vec![
             Term::Terminal(String::from("STRING B")),
             Term::Nonterminal(String::from("STRING C")),
         ]);
-        let p1: Production = Production::from_parts(lhs1, vec![rhs1]);
+        let p1 = Production::from_parts(lhs1, vec![rhs1]);
 
-        let lhs2: Term = Term::Nonterminal(String::from("STRING A"));
-        let rhs2: Expression = Expression::from_parts(vec![
+        let lhs2 = Term::Nonterminal(String::from("STRING A"));
+        let rhs2 = Expression::from_parts(vec![
             Term::Terminal(String::from("STRING B")),
             Term::Nonterminal(String::from("STRING C")),
         ]);
-        let mut p2: Production = Production::new();
+        let mut p2 = Production::new();
         p2.lhs = lhs2;
         p2.add_to_rhs(rhs2);
 
diff --git a/tests/display.rs b/tests/display.rs
index 93f308e..096ea0a 100644
--- a/tests/display.rs
+++ b/tests/display.rs
@@ -1,3 +1,5 @@
+#![cfg(test)]
+
 use bnf::Grammar;
 
 #[test]
diff --git a/tests/from_str.rs b/tests/from_str.rs
index c9105a8..b35c8cc 100644
--- a/tests/from_str.rs
+++ b/tests/from_str.rs
@@ -1,3 +1,5 @@
+#![cfg(test)]
+
 mod std_trait {
     use std::str::FromStr;
 
diff --git a/tests/grammar.rs b/tests/grammar.rs
index c7fc1fe..0f69cbc 100644
--- a/tests/grammar.rs
+++ b/tests/grammar.rs
@@ -1,3 +1,5 @@
+#![cfg(test)]
+
 use bnf::Grammar;
 use quickcheck::{Arbitrary, Gen, QuickCheck, TestResult};
 use rand::{rngs::StdRng, SeedableRng};
diff --git a/tests/iterate.rs b/tests/iterate.rs
index 1826417..9a19622 100644
--- a/tests/iterate.rs
+++ b/tests/iterate.rs
@@ -1,3 +1,5 @@
+#![cfg(test)]
+
 use bnf::{Grammar, Term};
 
 #[test]
diff --git a/tests/parse_input.rs b/tests/parse_input.rs
index 62176aa..1ce92bd 100644
--- a/tests/parse_input.rs
+++ b/tests/parse_input.rs
@@ -1,3 +1,5 @@
+#![cfg(test)]
+
 use bnf::Grammar;
 use insta::assert_snapshot;
 
@@ -75,7 +77,7 @@ fn recursive_nested_infinite() {
         .map(|a| a.to_string())
         .collect();
     assert_eq!(parses.len(), parse_count);
-    assert_snapshot!(parses[0..=3].join("\n"));
+    assert_snapshot!(parses.get(0..=3).unwrap().join("\n"));
 }
 
 #[test]
@@ -215,7 +217,7 @@ fn empty_first_nested() {
         .map(|a| a.to_string())
         .collect();
     assert_eq!(parses.len(), parse_count);
-    assert_snapshot!(parses[0..=3].join("\n"));
+    assert_snapshot!(parses.get(0..=3).unwrap().join("\n"));
 }
 
 #[test]
@@ -278,7 +280,7 @@ fn empty_noop_infinite() {
         .map(|a| a.to_string())
         .collect();
     assert_eq!(parses.len(), parse_count);
-    assert_snapshot!(parses[0..=3].join("\n"));
+    assert_snapshot!(parses.get(0..=3).unwrap().join("\n"));
 }
 
 // (source: <https://loup-vaillant.fr/tutorials/earley-parsing/recogniser>)
@@ -350,7 +352,7 @@ fn shared_nonterminal_failure() {
 fn swap_left_right_recursion() {
     let input = "aa a";
 
-    let left_recursive: &str = "
+    let left_recursive = "
         <conjunction> ::= <conjunction> <ws> <predicate> | <predicate>
         <predicate> ::= <string_null_one> | <special-string> '.'
         <string_null_one> ::= <string_null_two>
@@ -388,7 +390,7 @@ fn swap_left_right_recursion() {
 
 #[test]
 fn shared_nullable_nonterminal() {
-    let grammar: &str = "
+    let grammar = "
         <disjunction> ::= <predicate> | <disjunction> <or> <predicate>
         <predicate> ::= <char_null_one> | <special-string> '.'