diff --git a/Cargo.lock b/Cargo.lock
index 5fca5c19..67fa6d4a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -305,6 +305,7 @@ dependencies = [
  "serde_derive",
  "syntect",
  "toml",
+ "unic-langid",
  "utils",
 ]
 
@@ -2759,6 +2760,12 @@ dependencies = [
  "winapi 0.3.9",
 ]
 
+[[package]]
+name = "tinystr"
+version = "0.3.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "29738eedb4388d9ea620eeab9384884fc3f06f586a2eddb56bedc5885126c7c1"
+
 [[package]]
 name = "tinyvec"
 version = "1.1.1"
@@ -2898,6 +2905,24 @@ version = "0.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "80d7ff825a6a654ee85a63e80f92f054f904f21e7d12da4e22f9834a4aaa35bc"
 
+[[package]]
+name = "unic-langid"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "73328fcd730a030bdb19ddf23e192187a6b01cd98be6d3140622a89129459ce5"
+dependencies = [
+ "unic-langid-impl",
+]
+
+[[package]]
+name = "unic-langid-impl"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1a4a8eeaf0494862c1404c95ec2f4c33a2acff5076f64314b465e3ddae1b934d"
+dependencies = [
+ "tinystr",
+]
+
 [[package]]
 name = "unic-segment"
 version = "0.9.0"
diff --git a/components/config/Cargo.toml b/components/config/Cargo.toml
index 43bbcddb..97589409 100644
--- a/components/config/Cargo.toml
+++ b/components/config/Cargo.toml
@@ -13,6 +13,7 @@ chrono = "0.4"
 globset = "0.4"
 lazy_static = "1"
 syntect = "4.1"
+unic-langid = "0.9"
 
 errors = { path = "../errors" }
 utils = { path = "../utils" }
diff --git a/components/config/src/config/languages.rs b/components/config/src/config/languages.rs
index dee61ffb..20aaa00e 100644
--- a/components/config/src/config/languages.rs
+++ b/components/config/src/config/languages.rs
@@ -1,16 +1,31 @@
 use std::collections::HashMap;
 
+use errors::{bail, Result};
 use serde_derive::{Deserialize, Serialize};
+use unic_langid::LanguageIdentifier;
 
-#[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(default)]
-pub struct Language {
-    /// The language code
-    pub code: String,
+pub struct LanguageOptions {
     /// Whether to generate a feed for that language, defaults to `false`
-    pub feed: bool,
+    pub generate_feed: bool,
     /// Whether to generate search index for that language, defaults to `false`
-    pub search: bool,
+    pub build_search_index: bool,
+}
+
+impl Default for LanguageOptions {
+    fn default() -> Self {
+        LanguageOptions { generate_feed: false, build_search_index: false }
+    }
 }
 
 pub type TranslateTerm = HashMap<String, String>;
+
+/// We want to ensure the language codes are valid ones
+pub fn validate_code(code: &str) -> Result<()> {
+    if LanguageIdentifier::from_bytes(code.as_bytes()).is_err() {
+        bail!("Language `{}` is not a valid Unicode Language Identifier (see http://unicode.org/reports/tr35/#Unicode_language_identifier)", code)
+    }
+
+    Ok(())
+}
diff --git a/components/config/src/config/mod.rs b/components/config/src/config/mod.rs
index 57682b3b..70edef14 100644
--- a/components/config/src/config/mod.rs
+++ b/components/config/src/config/mod.rs
@@ -44,7 +44,7 @@ pub struct Config {
     /// The language used in the site. Defaults to "en"
     pub default_language: String,
     /// The list of supported languages outside of the default one
-    pub languages: Vec<languages::Language>,
+    pub languages: HashMap<String, languages::LanguageOptions>,
 
     /// Languages list and translated strings
     ///
@@ -129,10 +129,15 @@ impl Config {
             bail!("Highlight theme {} defined in config does not exist.", highlight_theme);
         }
 
-        if config.languages.iter().any(|l| l.code == config.default_language) {
+        if config.languages.iter().any(|(code, _)| code == &config.default_language) {
             bail!("Default language `{}` should not appear both in `config.default_language` and `config.languages`", config.default_language)
         }
 
+        languages::validate_code(&config.default_language)?;
+        for code in config.languages.keys() {
+            languages::validate_code(&code)?;
+        }
+
         if !config.ignored_content.is_empty() {
             // Convert the file glob strings into a compiled glob set matcher. We want to do this once,
             // at program initialization, rather than for every page, for example. We arrange for the
@@ -280,7 +285,7 @@ impl Config {
 
     /// Returns the codes of all additional languages
     pub fn languages_codes(&self) -> Vec<&str> {
-        self.languages.iter().map(|l| l.code.as_ref()).collect()
+        self.languages.iter().map(|(code, _)| code.as_ref()).collect()
     }
 
     pub fn is_in_build_mode(&self) -> bool {
@@ -362,7 +367,7 @@ impl Default for Config {
             highlight_code: false,
             highlight_theme: "base16-ocean-dark".to_string(),
             default_language: "en".to_string(),
-            languages: Vec::new(),
+            languages: HashMap::new(),
             generate_feed: false,
             feed_limit: None,
             feed_filename: "atom.xml".to_string(),
@@ -671,10 +676,11 @@ anchors = "off"
         let config_str = r#"
 base_url = "https://remplace-par-ton-url.fr"
 default_language = "fr"
-languages = [
-    { code = "fr" },
-    { code = "en" },
-]
+
+[languages.fr]
+
+[languages.en]
+
         "#;
         let config = Config::parse(config_str);
         let err = config.unwrap_err();
diff --git a/components/config/src/lib.rs b/components/config/src/lib.rs
index f431f232..0f5829ac 100644
--- a/components/config/src/lib.rs
+++ b/components/config/src/lib.rs
@@ -2,7 +2,7 @@ mod config;
 pub mod highlighting;
 mod theme;
 pub use crate::config::{
-    languages::Language, link_checker::LinkChecker, slugify::Slugify, taxonomies::Taxonomy, Config,
+    languages::LanguageOptions, link_checker::LinkChecker, slugify::Slugify, taxonomies::Taxonomy, Config,
 };
 use errors::Result;
 
diff --git a/components/library/src/content/file_info.rs b/components/library/src/content/file_info.rs
index 167d6048..d137ecb9 100644
--- a/components/library/src/content/file_info.rs
+++ b/components/library/src/content/file_info.rs
@@ -152,7 +152,7 @@ impl FileInfo {
 mod tests {
     use std::path::{Path, PathBuf};
 
-    use config::{Config, Language};
+    use config::{Config, LanguageOptions};
 
     use super::{find_content_components, FileInfo};
 
@@ -184,7 +184,7 @@ mod tests {
     #[test]
     fn can_find_valid_language_in_page() {
         let mut config = Config::default();
-        config.languages.push(Language { code: String::from("fr"), feed: false, search: false });
+        config.languages.insert("fr".to_owned(), LanguageOptions::default());
         let mut file = FileInfo::new_page(
             &Path::new("/home/vincent/code/site/content/posts/tutorials/python.fr.md"),
             &PathBuf::new(),
@@ -197,7 +197,7 @@ mod tests {
     #[test]
     fn can_find_valid_language_with_default_locale() {
         let mut config = Config::default();
-        config.languages.push(Language { code: String::from("fr"), feed: false, search: false });
+        config.languages.insert("fr".to_owned(), LanguageOptions::default());
         let mut file = FileInfo::new_page(
             &Path::new("/home/vincent/code/site/content/posts/tutorials/python.en.md"),
             &PathBuf::new(),
@@ -210,7 +210,7 @@ mod tests {
     #[test]
     fn can_find_valid_language_in_page_with_assets() {
         let mut config = Config::default();
-        config.languages.push(Language { code: String::from("fr"), feed: false, search: false });
+        config.languages.insert("fr".to_owned(), LanguageOptions::default());
         let mut file = FileInfo::new_page(
             &Path::new("/home/vincent/code/site/content/posts/tutorials/python/index.fr.md"),
             &PathBuf::new(),
@@ -236,7 +236,7 @@ mod tests {
     #[test]
     fn errors_on_unknown_language_in_page_with_i18n_on() {
         let mut config = Config::default();
-        config.languages.push(Language { code: String::from("it"), feed: false, search: false });
+        config.languages.insert("it".to_owned(), LanguageOptions::default());
         let mut file = FileInfo::new_page(
             &Path::new("/home/vincent/code/site/content/posts/tutorials/python.fr.md"),
             &PathBuf::new(),
@@ -248,7 +248,7 @@ mod tests {
     #[test]
     fn can_find_valid_language_in_section() {
         let mut config = Config::default();
-        config.languages.push(Language { code: String::from("fr"), feed: false, search: false });
+        config.languages.insert("fr".to_owned(), LanguageOptions::default());
         let mut file = FileInfo::new_section(
             &Path::new("/home/vincent/code/site/content/posts/tutorials/_index.fr.md"),
             &PathBuf::new(),
@@ -275,7 +275,7 @@ mod tests {
     #[test]
     fn correct_canonical_after_find_language() {
         let mut config = Config::default();
-        config.languages.push(Language { code: String::from("fr"), feed: false, search: false });
+        config.languages.insert("fr".to_owned(), LanguageOptions::default());
         let mut file = FileInfo::new_page(
             &Path::new("/home/vincent/code/site/content/posts/tutorials/python/index.fr.md"),
             &PathBuf::new(),
diff --git a/components/library/src/content/page.rs b/components/library/src/content/page.rs
index 7774dfcd..b0e8df85 100644
--- a/components/library/src/content/page.rs
+++ b/components/library/src/content/page.rs
@@ -333,7 +333,7 @@ mod tests {
     use tera::Tera;
 
     use super::Page;
-    use config::{Config, Language};
+    use config::{Config, LanguageOptions};
     use front_matter::InsertAnchor;
     use utils::slugs::SlugifyStrategy;
 
@@ -805,7 +805,7 @@ Hello world
     #[test]
     fn can_specify_language_in_filename() {
         let mut config = Config::default();
-        config.languages.push(Language { code: String::from("fr"), feed: false, search: false });
+        config.languages.insert("fr".to_owned(), LanguageOptions::default());
         let content = r#"
 +++
 +++
@@ -822,7 +822,7 @@ Bonjour le monde"#
     #[test]
     fn can_specify_language_in_filename_with_date() {
         let mut config = Config::default();
-        config.languages.push(Language { code: String::from("fr"), feed: false, search: false });
+        config.languages.insert("fr".to_owned(), LanguageOptions::default());
         let content = r#"
 +++
 +++
@@ -841,7 +841,7 @@ Bonjour le monde"#
     #[test]
     fn i18n_frontmatter_path_overrides_default_permalink() {
         let mut config = Config::default();
-        config.languages.push(Language { code: String::from("fr"), feed: false, search: false });
+        config.languages.insert("fr".to_owned(), LanguageOptions::default());
         let content = r#"
 +++
 path = "bonjour"
diff --git a/components/library/src/content/section.rs b/components/library/src/content/section.rs
index 299af1a5..00c9024f 100644
--- a/components/library/src/content/section.rs
+++ b/components/library/src/content/section.rs
@@ -254,7 +254,7 @@ mod tests {
     use tempfile::tempdir;
 
     use super::Section;
-    use config::{Config, Language};
+    use config::{Config, LanguageOptions};
 
     #[test]
     fn section_with_assets_gets_right_info() {
@@ -312,7 +312,7 @@ mod tests {
     #[test]
     fn can_specify_language_in_filename() {
         let mut config = Config::default();
-        config.languages.push(Language { code: String::from("fr"), feed: false, search: false });
+        config.languages.insert("fr".to_owned(), LanguageOptions::default());
         let content = r#"
 +++
 +++
@@ -334,7 +334,7 @@ Bonjour le monde"#
     #[test]
     fn can_make_links_to_translated_sections_without_double_trailing_slash() {
         let mut config = Config::default();
-        config.languages.push(Language { code: String::from("fr"), feed: false, search: false });
+        config.languages.insert("fr".to_owned(), LanguageOptions::default());
         let content = r#"
 +++
 +++
@@ -351,7 +351,7 @@ Bonjour le monde"#
     #[test]
     fn can_make_links_to_translated_subsections_with_trailing_slash() {
         let mut config = Config::default();
-        config.languages.push(Language { code: String::from("fr"), feed: false, search: false });
+        config.languages.insert("fr".to_owned(), LanguageOptions::default());
         let content = r#"
 +++
 +++
diff --git a/components/library/src/taxonomies/mod.rs b/components/library/src/taxonomies/mod.rs
index f4660d1b..d3291678 100644
--- a/components/library/src/taxonomies/mod.rs
+++ b/components/library/src/taxonomies/mod.rs
@@ -270,7 +270,7 @@ mod tests {
 
     use crate::content::Page;
     use crate::library::Library;
-    use config::{Config, Language, Slugify, Taxonomy as TaxonomyConfig};
+    use config::{Config, LanguageOptions, Slugify, Taxonomy as TaxonomyConfig};
     use utils::slugs::SlugifyStrategy;
 
     #[test]
@@ -495,7 +495,7 @@ mod tests {
     #[test]
     fn can_make_taxonomies_in_multiple_languages() {
         let mut config = Config::default();
-        config.languages.push(Language { feed: false, code: "fr".to_string(), search: false });
+        config.languages.insert("fr".to_owned(), LanguageOptions::default());
         let mut library = Library::new(2, 0, true);
 
         config.taxonomies = vec![
@@ -605,11 +605,7 @@ mod tests {
     fn can_make_utf8_taxonomies() {
         let mut config = Config::default();
         config.slugify.taxonomies = SlugifyStrategy::Safe;
-        config.languages.push(Language {
-            feed: false,
-            code: "fr".to_string(),
-            ..Language::default()
-        });
+        config.languages.insert("fr".to_owned(), LanguageOptions::default());
         let mut library = Library::new(2, 0, true);
 
         config.taxonomies = vec![TaxonomyConfig {
@@ -638,11 +634,7 @@ mod tests {
     fn can_make_slugified_taxonomies_in_multiple_languages() {
         let mut config = Config::default();
         config.slugify.taxonomies = SlugifyStrategy::On;
-        config.languages.push(Language {
-            feed: false,
-            code: "fr".to_string(),
-            ..Language::default()
-        });
+        config.languages.insert("fr".to_owned(), LanguageOptions::default());
         let mut library = Library::new(2, 0, true);
 
         config.taxonomies = vec![
diff --git a/components/site/src/lib.rs b/components/site/src/lib.rs
index 97704778..bf725abf 100644
--- a/components/site/src/lib.rs
+++ b/components/site/src/lib.rs
@@ -126,11 +126,8 @@ impl Site {
     /// There are one index section for the default language + 1 per language
     fn index_section_paths(&self) -> Vec<(PathBuf, Option<String>)> {
         let mut res = vec![(self.content_path.join("_index.md"), None)];
-        for language in &self.config.languages {
-            res.push((
-                self.content_path.join(format!("_index.{}.md", language.code)),
-                Some(language.code.clone()),
-            ));
+        for code in self.config.languages.keys() {
+            res.push((self.content_path.join(format!("_index.{}.md", code)), Some(code.clone())));
         }
         res
     }
@@ -177,7 +174,7 @@ impl Site {
         // so it's kinda necessecary
         let mut dir_walker = WalkDir::new(format!("{}/{}", base_path, "content/")).into_iter();
         let mut allowed_index_filenames: Vec<_> =
-            self.config.languages.iter().map(|l| format!("_index.{}.md", l.code)).collect();
+            self.config.languages.iter().map(|(code, _)| format!("_index.{}.md", code)).collect();
         allowed_index_filenames.push("_index.md".to_string());
 
         loop {
@@ -228,7 +225,7 @@ impl Site {
                         Ok(f) => {
                             let path_str = f.path().file_name().unwrap().to_str().unwrap();
                             if f.path().is_file()
-                                && allowed_index_filenames.iter().find(|&s| *s == path_str).is_some()
+                                && allowed_index_filenames.iter().any(|s| s == path_str)
                             {
                                 Some(f)
                             } else {
@@ -660,13 +657,13 @@ impl Site {
             start = log_time(start, "Generated feed in default language");
         }
 
-        for lang in &self.config.languages {
-            if !lang.feed {
+        for (code, language) in &self.config.languages {
+            if !language.generate_feed {
                 continue;
             }
             let pages =
-                library.pages_values().iter().filter(|p| p.lang == lang.code).cloned().collect();
-            self.render_feed(pages, Some(&PathBuf::from(lang.code.clone())), &lang.code, |c| c)?;
+                library.pages_values().iter().filter(|p| &p.lang == code).cloned().collect();
+            self.render_feed(pages, Some(&PathBuf::from(code)), &code, |c| c)?;
             start = log_time(start, "Generated feed in other language");
         }
 
@@ -704,17 +701,13 @@ impl Site {
             ),
         )?;
 
-        for language in &self.config.languages {
-            if language.code != self.config.default_language && language.search {
+        for (code, language) in &self.config.languages {
+            if code != &self.config.default_language && language.build_search_index {
                 create_file(
-                    &self.output_path.join(&format!("search_index.{}.js", &language.code)),
+                    &self.output_path.join(&format!("search_index.{}.js", &code)),
                     &format!(
                         "window.searchIndex = {};",
-                        search::build_index(
-                            &language.code,
-                            &self.library.read().unwrap(),
-                            &self.config
-                        )?
+                        search::build_index(&code, &self.library.read().unwrap(), &self.config)?
                     ),
                 )?;
             }
diff --git a/components/templates/src/global_fns/mod.rs b/components/templates/src/global_fns/mod.rs
index 7038c157..fa71cf75 100644
--- a/components/templates/src/global_fns/mod.rs
+++ b/components/templates/src/global_fns/mod.rs
@@ -67,7 +67,7 @@ fn make_path_with_lang(path: String, lang: &str, config: &Config) -> Result<Stri
         return Ok(path);
     }
 
-    if !config.languages.iter().any(|x| x.code == lang) {
+    if !config.languages.iter().any(|(x, _)| x == lang) {
         return Err(
             format!("`{}` is not an authorized language (check config.languages).", lang).into()
         );
@@ -728,9 +728,9 @@ mod tests {
     const TRANS_CONFIG: &str = r#"
 base_url = "https://remplace-par-ton-url.fr"
 default_language = "fr"
-languages = [
-    { code = "en" },
-]
+
+[languages]
+[languages.en]
 
 [translations]
 [translations.fr]
diff --git a/test_site_i18n/config.toml b/test_site_i18n/config.toml
index e1c692f4..3f8da069 100644
--- a/test_site_i18n/config.toml
+++ b/test_site_i18n/config.toml
@@ -18,10 +18,11 @@ taxonomies = [
     {name = "tags", lang = "fr"},
 ]
 
-languages = [
- {code = "fr", feed = true},
- {code = "it", feed = false, search = true },
-]
+[languages.fr]
+generate_feed = true
+
+[languages.it]
+build_search_index = true
 
 [markdown]
 highlight_code = false