diff --git a/benches/corrections.rs b/benches/corrections.rs
index b849986..8e0d751 100644
--- a/benches/corrections.rs
+++ b/benches/corrections.rs
@@ -4,12 +4,12 @@ extern crate test;
 
 #[bench]
 fn load_corrections(b: &mut test::Bencher) {
-    b.iter(|| typos::Dictionary::new());
+    b.iter(|| typos::BuiltIn::new());
 }
 
 #[bench]
 fn correct_word_hit(b: &mut test::Bencher) {
-    let corrections = typos::Dictionary::new();
+    let corrections = typos::BuiltIn::new();
     let input = typos::tokens::Word::new("successs", 0).unwrap();
     assert_eq!(
         corrections.correct_word(input),
@@ -20,7 +20,7 @@ fn correct_word_hit(b: &mut test::Bencher) {
 
 #[bench]
 fn correct_word_miss(b: &mut test::Bencher) {
-    let corrections = typos::Dictionary::new();
+    let corrections = typos::BuiltIn::new();
     let input = typos::tokens::Word::new("success", 0).unwrap();
     assert_eq!(corrections.correct_word(input), None);
     b.iter(|| corrections.correct_word(input));
diff --git a/benches/file.rs b/benches/file.rs
index d25c7d1..0783e86 100644
--- a/benches/file.rs
+++ b/benches/file.rs
@@ -12,7 +12,7 @@ fn process_empty(b: &mut test::Bencher) {
     let sample_path = temp.child("sample");
     sample_path.write_str(data::EMPTY).unwrap();
 
-    let corrections = typos::Dictionary::new();
+    let corrections = typos::BuiltIn::new();
     let parser = typos::tokens::Parser::new();
     let checks = typos::checks::CheckSettings::new().build(&corrections, &parser);
     b.iter(|| checks.check_file(sample_path.path(), typos::report::print_silent));
@@ -26,7 +26,7 @@ fn process_no_tokens(b: &mut test::Bencher) {
     let sample_path = temp.child("sample");
     sample_path.write_str(data::NO_TOKENS).unwrap();
 
-    let corrections = typos::Dictionary::new();
+    let corrections = typos::BuiltIn::new();
     let parser = typos::tokens::Parser::new();
     let checks = typos::checks::CheckSettings::new().build(&corrections, &parser);
     b.iter(|| checks.check_file(sample_path.path(), typos::report::print_silent));
@@ -40,7 +40,7 @@ fn process_single_token(b: &mut test::Bencher) {
     let sample_path = temp.child("sample");
     sample_path.write_str(data::SINGLE_TOKEN).unwrap();
 
-    let corrections = typos::Dictionary::new();
+    let corrections = typos::BuiltIn::new();
     let parser = typos::tokens::Parser::new();
     let checks = typos::checks::CheckSettings::new().build(&corrections, &parser);
     b.iter(|| checks.check_file(sample_path.path(), typos::report::print_silent));
@@ -54,7 +54,7 @@ fn process_sherlock(b: &mut test::Bencher) {
     let sample_path = temp.child("sample");
     sample_path.write_str(data::SHERLOCK).unwrap();
 
-    let corrections = typos::Dictionary::new();
+    let corrections = typos::BuiltIn::new();
     let parser = typos::tokens::Parser::new();
     let checks = typos::checks::CheckSettings::new().build(&corrections, &parser);
     b.iter(|| checks.check_file(sample_path.path(), typos::report::print_silent));
@@ -68,7 +68,7 @@ fn process_code(b: &mut test::Bencher) {
     let sample_path = temp.child("sample");
     sample_path.write_str(data::CODE).unwrap();
 
-    let corrections = typos::Dictionary::new();
+    let corrections = typos::BuiltIn::new();
     let parser = typos::tokens::Parser::new();
     let checks = typos::checks::CheckSettings::new().build(&corrections, &parser);
     b.iter(|| checks.check_file(sample_path.path(), typos::report::print_silent));
@@ -82,7 +82,7 @@ fn process_corpus(b: &mut test::Bencher) {
     let sample_path = temp.child("sample");
     sample_path.write_str(data::CORPUS).unwrap();
 
-    let corrections = typos::Dictionary::new();
+    let corrections = typos::BuiltIn::new();
     let parser = typos::tokens::Parser::new();
     let checks = typos::checks::CheckSettings::new().build(&corrections, &parser);
     b.iter(|| checks.check_file(sample_path.path(), typos::report::print_silent));
diff --git a/src/dict.rs b/src/dict.rs
index 1861757..1ff7359 100644
--- a/src/dict.rs
+++ b/src/dict.rs
@@ -4,12 +4,21 @@ use unicase::UniCase;
 
 use crate::tokens::Case;
 
-#[derive(Default)]
-pub struct Dictionary {}
+pub trait Dictionary {
+    fn correct_ident<'s, 'w>(
+        &'s self,
+        _ident: crate::tokens::Identifier<'w>,
+    ) -> Option<Cow<'s, str>>;
 
-impl Dictionary {
+    fn correct_word<'s, 'w>(&'s self, word: crate::tokens::Word<'w>) -> Option<Cow<'s, str>>;
+}
+
+#[derive(Default)]
+pub struct BuiltIn {}
+
+impl BuiltIn {
     pub fn new() -> Self {
-        Dictionary {}
+        Self {}
     }
 
     pub fn correct_ident<'s, 'w>(
@@ -25,6 +34,19 @@ impl Dictionary {
     }
 }
 
+impl Dictionary for BuiltIn {
+    fn correct_ident<'s, 'w>(
+        &'s self,
+        ident: crate::tokens::Identifier<'w>,
+    ) -> Option<Cow<'s, str>> {
+        BuiltIn::correct_ident(self, ident)
+    }
+
+    fn correct_word<'s, 'w>(&'s self, word: crate::tokens::Word<'w>) -> Option<Cow<'s, str>> {
+        BuiltIn::correct_word(self, word)
+    }
+}
+
 fn map_lookup(
     map: &'static phf::Map<UniCase<&'static str>, &'static str>,
     key: &str,
diff --git a/src/main.rs b/src/main.rs
index efe688e..8673f7e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -260,7 +260,7 @@ fn run() -> Result<i32, failure::Error> {
     let ignore_hex = options.ignore_hex().unwrap_or(true);
     let binary = options.binary().unwrap_or(false);
 
-    let dictionary = typos::Dictionary::new();
+    let dictionary = typos::BuiltIn::new();
 
     let parser = typos::tokens::ParserBuilder::new()
         .ignore_hex(ignore_hex)