diff --git a/benches/checks.rs b/benches/checks.rs
index 77b4743..9b7f97d 100644
--- a/benches/checks.rs
+++ b/benches/checks.rs
@@ -5,10 +5,10 @@ use criterion::{criterion_group, criterion_main, BenchmarkId, Criterion};
 use typos_cli::file::FileChecker;
 
 fn bench_checks(c: &mut Criterion) {
-    let dictionary = typos_cli::dict::BuiltIn::new(Default::default());
+    let dict = typos_cli::dict::BuiltIn::new(Default::default());
     let tokenizer = typos::tokens::Tokenizer::new();
     let policy = typos_cli::policy::Policy::new()
-        .dictionary(&dictionary)
+        .dict(&dict)
         .tokenizer(&tokenizer);
 
     let mut group = c.benchmark_group("checks");
diff --git a/docs/reference.md b/docs/reference.md
index 7720c4c..32039da 100644
--- a/docs/reference.md
+++ b/docs/reference.md
@@ -28,6 +28,6 @@ Configuration is read from the following (in precedence order)
 | default.identifier-include-digits   | \-   | bool   | Allow identifiers to include digits, in addition to letters. |
 | default.identifier-leading-chars    | \-   | string | Allow identifiers to start with one of these characters. |
 | default.identifier-include-chars    | \-   | string | Allow identifiers to include these characters. |
-| default.locale         | \-                | en, en-us, en-gb, en-ca, en-au   | English dialect to correct to. |
+| default.locale         | --locale          | en, en-us, en-gb, en-ca, en-au   | English dialect to correct to. |
 | default.extend-identifiers | \-            | table of strings | Corrections for identifiers. When the correction is blank, the word is never valid. When the correction is the key, the word is always valid. |
 | default.extend-words       | \-            | table of strings | Corrections for identifiers. When the correction is blank, the word is never valid. When the correction is the key, the word is always valid. |
diff --git a/src/args.rs b/src/args.rs
index 53ae795..2c9c1db 100644
--- a/src/args.rs
+++ b/src/args.rs
@@ -122,12 +122,6 @@ pub(crate) struct FileArgs {
     #[structopt(long, overrides_with("no-check-files"), hidden(true))]
     check_files: bool,
 
-    #[structopt(long, overrides_with("hex"))]
-    /// Don't try to detect that an identifier looks like hex
-    no_hex: bool,
-    #[structopt(long, overrides_with("no-hex"), hidden(true))]
-    hex: bool,
-
     #[structopt(
         long,
         possible_values(&config::Locale::variants()),
@@ -163,15 +157,12 @@ impl config::FileSource for FileArgs {
         }
     }
 
-    fn ignore_hex(&self) -> Option<bool> {
-        match (self.hex, self.no_hex) {
-            (true, false) => Some(true),
-            (false, true) => Some(false),
-            (false, false) => None,
-            (_, _) => unreachable!("StructOpt should make this impossible"),
-        }
+    fn dict(&self) -> Option<&dyn config::DictSource> {
+        Some(self)
     }
+}
 
+impl config::DictSource for FileArgs {
     fn locale(&self) -> Option<config::Locale> {
         self.locale
     }
diff --git a/src/config.rs b/src/config.rs
index 2fcbc63..1423ae9 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -58,6 +58,16 @@ pub trait FileSource {
         None
     }
 
+    fn tokenizer(&self) -> Option<&dyn TokenizerSource> {
+        None
+    }
+
+    fn dict(&self) -> Option<&dyn DictSource> {
+        None
+    }
+}
+
+pub trait TokenizerSource {
     /// Do not check identifiers that appear to be hexadecimal values.
     fn ignore_hex(&self) -> Option<bool> {
         None
@@ -82,7 +92,9 @@ pub trait FileSource {
     fn identifier_include_chars(&self) -> Option<&str> {
         None
     }
+}
 
+pub trait DictSource {
     fn locale(&self) -> Option<Locale> {
         None
     }
@@ -258,14 +270,10 @@ pub struct FileConfig {
     pub binary: Option<bool>,
     pub check_filename: Option<bool>,
     pub check_file: Option<bool>,
-    pub ignore_hex: Option<bool>,
-    pub identifier_leading_digits: Option<bool>,
-    pub identifier_leading_chars: Option<kstring::KString>,
-    pub identifier_include_digits: Option<bool>,
-    pub identifier_include_chars: Option<kstring::KString>,
-    pub locale: Option<Locale>,
-    pub extend_identifiers: HashMap<kstring::KString, kstring::KString>,
-    pub extend_words: HashMap<kstring::KString, kstring::KString>,
+    #[serde(flatten)]
+    pub tokenizer: Option<TokenizerConfig>,
+    #[serde(flatten)]
+    pub dict: Option<DictConfig>,
 }
 
 impl FileConfig {
@@ -275,18 +283,12 @@ impl FileConfig {
             binary: Some(empty.binary()),
             check_filename: Some(empty.check_filename()),
             check_file: Some(empty.check_file()),
-            ignore_hex: Some(empty.ignore_hex()),
-            identifier_leading_digits: Some(empty.identifier_leading_digits()),
-            identifier_leading_chars: Some(kstring::KString::from_ref(
-                empty.identifier_leading_chars(),
-            )),
-            identifier_include_digits: Some(empty.identifier_include_digits()),
-            identifier_include_chars: Some(kstring::KString::from_ref(
-                empty.identifier_include_chars(),
-            )),
-            locale: Some(empty.locale()),
-            extend_identifiers: Default::default(),
-            extend_words: Default::default(),
+            tokenizer: Some(
+                empty
+                    .tokenizer
+                    .unwrap_or_else(|| TokenizerConfig::from_defaults()),
+            ),
+            dict: Some(empty.dict.unwrap_or_else(|| DictConfig::from_defaults())),
         }
     }
 
@@ -300,6 +302,87 @@ impl FileConfig {
         if let Some(source) = source.check_file() {
             self.check_file = Some(source);
         }
+        if let Some(source) = source.tokenizer() {
+            let mut tokenizer = None;
+            std::mem::swap(&mut tokenizer, &mut self.tokenizer);
+            let mut tokenizer = tokenizer.unwrap_or_default();
+            tokenizer.update(source);
+            let mut tokenizer = Some(tokenizer);
+            std::mem::swap(&mut tokenizer, &mut self.tokenizer);
+        }
+        if let Some(source) = source.dict() {
+            let mut dict = None;
+            std::mem::swap(&mut dict, &mut self.dict);
+            let mut dict = dict.unwrap_or_default();
+            dict.update(source);
+            let mut dict = Some(dict);
+            std::mem::swap(&mut dict, &mut self.dict);
+        }
+    }
+
+    pub fn binary(&self) -> bool {
+        self.binary.unwrap_or(false)
+    }
+
+    pub fn check_filename(&self) -> bool {
+        self.check_filename.unwrap_or(true)
+    }
+
+    pub fn check_file(&self) -> bool {
+        self.check_file.unwrap_or(true)
+    }
+}
+
+impl FileSource for FileConfig {
+    fn binary(&self) -> Option<bool> {
+        self.binary
+    }
+
+    fn check_filename(&self) -> Option<bool> {
+        self.check_filename
+    }
+
+    fn check_file(&self) -> Option<bool> {
+        self.check_file
+    }
+
+    fn tokenizer(&self) -> Option<&dyn TokenizerSource> {
+        self.tokenizer.as_ref().map(|t| t as &dyn TokenizerSource)
+    }
+
+    fn dict(&self) -> Option<&dyn DictSource> {
+        self.dict.as_ref().map(|d| d as &dyn DictSource)
+    }
+}
+
+#[derive(Debug, Clone, Default, serde::Serialize, serde::Deserialize)]
+#[serde(deny_unknown_fields, default)]
+#[serde(rename_all = "kebab-case")]
+pub struct TokenizerConfig {
+    pub ignore_hex: Option<bool>,
+    pub identifier_leading_digits: Option<bool>,
+    pub identifier_leading_chars: Option<kstring::KString>,
+    pub identifier_include_digits: Option<bool>,
+    pub identifier_include_chars: Option<kstring::KString>,
+}
+
+impl TokenizerConfig {
+    pub fn from_defaults() -> Self {
+        let empty = Self::default();
+        Self {
+            ignore_hex: Some(empty.ignore_hex()),
+            identifier_leading_digits: Some(empty.identifier_leading_digits()),
+            identifier_leading_chars: Some(kstring::KString::from_ref(
+                empty.identifier_leading_chars(),
+            )),
+            identifier_include_digits: Some(empty.identifier_include_digits()),
+            identifier_include_chars: Some(kstring::KString::from_ref(
+                empty.identifier_include_chars(),
+            )),
+        }
+    }
+
+    pub fn update(&mut self, source: &dyn TokenizerSource) {
         if let Some(source) = source.ignore_hex() {
             self.ignore_hex = Some(source);
         }
@@ -315,31 +398,6 @@ impl FileConfig {
         if let Some(source) = source.identifier_include_chars() {
             self.identifier_include_chars = Some(kstring::KString::from_ref(source));
         }
-        if let Some(source) = source.locale() {
-            self.locale = Some(source);
-        }
-        self.extend_identifiers.extend(
-            source
-                .extend_identifiers()
-                .map(|(k, v)| (kstring::KString::from_ref(k), kstring::KString::from_ref(v))),
-        );
-        self.extend_words.extend(
-            source
-                .extend_words()
-                .map(|(k, v)| (kstring::KString::from_ref(k), kstring::KString::from_ref(v))),
-        );
-    }
-
-    pub fn binary(&self) -> bool {
-        self.binary.unwrap_or(false)
-    }
-
-    pub fn check_filename(&self) -> bool {
-        self.check_filename.unwrap_or(true)
-    }
-
-    pub fn check_file(&self) -> bool {
-        self.check_file.unwrap_or(true)
     }
 
     pub fn ignore_hex(&self) -> bool {
@@ -361,6 +419,64 @@ impl FileConfig {
     pub fn identifier_include_chars(&self) -> &str {
         self.identifier_include_chars.as_deref().unwrap_or("_'")
     }
+}
+
+impl TokenizerSource for TokenizerConfig {
+    fn ignore_hex(&self) -> Option<bool> {
+        self.ignore_hex
+    }
+
+    fn identifier_leading_digits(&self) -> Option<bool> {
+        self.identifier_leading_digits
+    }
+
+    fn identifier_leading_chars(&self) -> Option<&str> {
+        self.identifier_leading_chars.as_deref()
+    }
+
+    fn identifier_include_digits(&self) -> Option<bool> {
+        self.identifier_include_digits
+    }
+
+    fn identifier_include_chars(&self) -> Option<&str> {
+        self.identifier_include_chars.as_deref()
+    }
+}
+
+#[derive(Debug, Clone, Default, serde::Serialize, serde::Deserialize)]
+#[serde(deny_unknown_fields, default)]
+#[serde(rename_all = "kebab-case")]
+pub struct DictConfig {
+    pub locale: Option<Locale>,
+    pub extend_identifiers: HashMap<kstring::KString, kstring::KString>,
+    pub extend_words: HashMap<kstring::KString, kstring::KString>,
+}
+
+impl DictConfig {
+    pub fn from_defaults() -> Self {
+        let empty = Self::default();
+        Self {
+            locale: Some(empty.locale()),
+            extend_identifiers: Default::default(),
+            extend_words: Default::default(),
+        }
+    }
+
+    pub fn update(&mut self, source: &dyn DictSource) {
+        if let Some(source) = source.locale() {
+            self.locale = Some(source);
+        }
+        self.extend_identifiers.extend(
+            source
+                .extend_identifiers()
+                .map(|(k, v)| (kstring::KString::from_ref(k), kstring::KString::from_ref(v))),
+        );
+        self.extend_words.extend(
+            source
+                .extend_words()
+                .map(|(k, v)| (kstring::KString::from_ref(k), kstring::KString::from_ref(v))),
+        );
+    }
 
     pub fn locale(&self) -> Locale {
         self.locale.unwrap_or_default()
@@ -383,39 +499,7 @@ impl FileConfig {
     }
 }
 
-impl FileSource for FileConfig {
-    fn binary(&self) -> Option<bool> {
-        self.binary
-    }
-
-    fn check_filename(&self) -> Option<bool> {
-        self.check_filename
-    }
-
-    fn check_file(&self) -> Option<bool> {
-        self.check_file
-    }
-
-    fn ignore_hex(&self) -> Option<bool> {
-        self.ignore_hex
-    }
-
-    fn identifier_leading_digits(&self) -> Option<bool> {
-        self.identifier_leading_digits
-    }
-
-    fn identifier_leading_chars(&self) -> Option<&str> {
-        self.identifier_leading_chars.as_deref()
-    }
-
-    fn identifier_include_digits(&self) -> Option<bool> {
-        self.identifier_include_digits
-    }
-
-    fn identifier_include_chars(&self) -> Option<&str> {
-        self.identifier_include_chars.as_deref()
-    }
-
+impl DictSource for DictConfig {
     fn locale(&self) -> Option<Locale> {
         self.locale
     }
diff --git a/src/file.rs b/src/file.rs
index 240763f..bc2015e 100644
--- a/src/file.rs
+++ b/src/file.rs
@@ -28,7 +28,7 @@ impl FileChecker for Typos {
     ) -> Result<(), std::io::Error> {
         if policy.check_filenames {
             if let Some(file_name) = path.file_name().and_then(|s| s.to_str()) {
-                for typo in typos::check_str(file_name, policy.tokenizer, policy.dictionary) {
+                for typo in typos::check_str(file_name, policy.tokenizer, policy.dict) {
                     let msg = report::Typo {
                         context: Some(report::PathContext { path }.into()),
                         buffer: std::borrow::Cow::Borrowed(file_name.as_bytes()),
@@ -48,7 +48,7 @@ impl FileChecker for Typos {
                 reporter.report(msg.into())?;
             } else {
                 let mut accum_line_num = AccumulateLineNum::new();
-                for typo in typos::check_bytes(&buffer, policy.tokenizer, policy.dictionary) {
+                for typo in typos::check_bytes(&buffer, policy.tokenizer, policy.dict) {
                     let line_num = accum_line_num.line_num(&buffer, typo.byte_offset);
                     let (line, line_offset) = extract_line(&buffer, typo.byte_offset);
                     let msg = report::Typo {
@@ -86,7 +86,7 @@ impl FileChecker for FixTypos {
             } else {
                 let mut fixes = Vec::new();
                 let mut accum_line_num = AccumulateLineNum::new();
-                for typo in typos::check_bytes(&buffer, policy.tokenizer, policy.dictionary) {
+                for typo in typos::check_bytes(&buffer, policy.tokenizer, policy.dict) {
                     if is_fixable(&typo) {
                         fixes.push(typo.into_owned());
                     } else {
@@ -113,7 +113,7 @@ impl FileChecker for FixTypos {
         if policy.check_filenames {
             if let Some(file_name) = path.file_name().and_then(|s| s.to_str()) {
                 let mut fixes = Vec::new();
-                for typo in typos::check_str(file_name, policy.tokenizer, policy.dictionary) {
+                for typo in typos::check_str(file_name, policy.tokenizer, policy.dict) {
                     if is_fixable(&typo) {
                         fixes.push(typo.into_owned());
                     } else {
@@ -163,7 +163,7 @@ impl FileChecker for DiffTypos {
             } else {
                 let mut fixes = Vec::new();
                 let mut accum_line_num = AccumulateLineNum::new();
-                for typo in typos::check_bytes(&buffer, policy.tokenizer, policy.dictionary) {
+                for typo in typos::check_bytes(&buffer, policy.tokenizer, policy.dict) {
                     if is_fixable(&typo) {
                         fixes.push(typo.into_owned());
                     } else {
@@ -191,7 +191,7 @@ impl FileChecker for DiffTypos {
         if policy.check_filenames {
             if let Some(file_name) = path.file_name().and_then(|s| s.to_str()) {
                 let mut fixes = Vec::new();
-                for typo in typos::check_str(file_name, policy.tokenizer, policy.dictionary) {
+                for typo in typos::check_str(file_name, policy.tokenizer, policy.dict) {
                     if is_fixable(&typo) {
                         fixes.push(typo.into_owned());
                     } else {
diff --git a/src/policy.rs b/src/policy.rs
index f5bc6ac..fb032f9 100644
--- a/src/policy.rs
+++ b/src/policy.rs
@@ -20,41 +20,50 @@ pub struct ConfigEngine<'s> {
     check_files: bool,
     binary: bool,
     tokenizer: typos::tokens::Tokenizer,
-    dictionary: crate::dict::Override<'s, 's, crate::dict::BuiltIn>,
+    dict: crate::dict::Override<'s, 's, crate::dict::BuiltIn>,
 }
 
 impl<'s> ConfigEngine<'s> {
     pub fn new(config: crate::config::Config, storage: &'s ConfigStorage) -> Self {
         let crate::config::Config { files, default } = config;
+        let binary = default.binary();
+        let check_filename = default.check_filename();
+        let check_file = default.check_file();
+        let crate::config::EngineConfig {
+            tokenizer, dict, ..
+        } = default;
+        let tokenizer_config =
+            tokenizer.unwrap_or_else(|| crate::config::TokenizerConfig::from_defaults());
+        let dict_config = dict.unwrap_or_else(|| crate::config::DictConfig::from_defaults());
 
         let tokenizer = typos::tokens::TokenizerBuilder::new()
-            .ignore_hex(default.ignore_hex())
-            .leading_digits(default.identifier_leading_digits())
-            .leading_chars(default.identifier_leading_chars().to_owned())
-            .include_digits(default.identifier_include_digits())
-            .include_chars(default.identifier_include_chars().to_owned())
+            .ignore_hex(tokenizer_config.ignore_hex())
+            .leading_digits(tokenizer_config.identifier_leading_digits())
+            .leading_chars(tokenizer_config.identifier_leading_chars().to_owned())
+            .include_digits(tokenizer_config.identifier_include_digits())
+            .include_chars(tokenizer_config.identifier_include_chars().to_owned())
             .build();
 
-        let dictionary = crate::dict::BuiltIn::new(default.locale());
-        let mut dictionary = crate::dict::Override::new(dictionary);
-        dictionary.identifiers(
-            default
+        let dict = crate::dict::BuiltIn::new(dict_config.locale());
+        let mut dict = crate::dict::Override::new(dict);
+        dict.identifiers(
+            dict_config
                 .extend_identifiers()
                 .map(|(k, v)| (storage.get(k), storage.get(v))),
         );
-        dictionary.words(
-            default
+        dict.words(
+            dict_config
                 .extend_words()
                 .map(|(k, v)| (storage.get(k), storage.get(v))),
         );
 
         Self {
             files,
-            check_filenames: default.check_filename(),
-            check_files: default.check_file(),
-            binary: default.binary(),
+            check_filenames: check_filename,
+            check_files: check_file,
+            binary: binary,
             tokenizer,
-            dictionary,
+            dict,
         }
     }
 
@@ -68,7 +77,7 @@ impl<'s> ConfigEngine<'s> {
             check_files: self.check_files,
             binary: self.binary,
             tokenizer: &self.tokenizer,
-            dictionary: &self.dictionary,
+            dict: &self.dict,
         }
     }
 }
@@ -80,7 +89,7 @@ pub struct Policy<'t, 'd> {
     pub check_files: bool,
     pub binary: bool,
     pub tokenizer: &'t typos::tokens::Tokenizer,
-    pub dictionary: &'d dyn typos::Dictionary,
+    pub dict: &'d dyn typos::Dictionary,
 }
 
 impl<'t, 'd> Policy<'t, 'd> {
@@ -100,7 +109,7 @@ impl<'t, 'd> Default for Policy<'t, 'd> {
             check_files: true,
             binary: false,
             tokenizer: &DEFAULT_TOKENIZER,
-            dictionary: &DEFAULT_DICT,
+            dict: &DEFAULT_DICT,
         }
     }
 }