diff --git a/demo_hornbeam_project/src/main.rs b/demo_hornbeam_project/src/main.rs
index 19bb9fb..9884a74 100644
--- a/demo_hornbeam_project/src/main.rs
+++ b/demo_hornbeam_project/src/main.rs
@@ -38,16 +38,10 @@ async fn main() -> eyre::Result<()> {
     Ok(())
 }
 
-async fn say_hello(Path((_lang, name)): Path<(String, String)>) -> impl IntoResponse {
-    // TODO This should be translated with Fluent!
-
-    //let template = templates.prepare("say_hello", None, Params::default().set("name", name));
-
-    Rendered(render_template_string!(TEMPLATING, say_hello, "en-GB", {
+async fn say_hello(Path((lang, name)): Path<(String, String)>) -> impl IntoResponse {
+    Rendered(render_template_string!(TEMPLATING, say_hello, lang, {
         name: name
     }))
-
-    // HtmlTemplate(template)
 }
 
 struct Rendered(Result<String, hornbeam::TemplateError>);
diff --git a/demo_hornbeam_project/translations/fr-FR/say_hello.ftl b/demo_hornbeam_project/translations/fr-FR/say_hello.ftl
new file mode 100644
index 0000000..f528eb6
--- /dev/null
+++ b/demo_hornbeam_project/translations/fr-FR/say_hello.ftl
@@ -0,0 +1 @@
+hello = Bonjour { $name } !
diff --git a/hornbeam/src/interpreted.rs b/hornbeam/src/interpreted.rs
index f75c640..97f2ee7 100644
--- a/hornbeam/src/interpreted.rs
+++ b/hornbeam/src/interpreted.rs
@@ -10,7 +10,6 @@ use hornbeam_interpreter::localisation::fluent::{
     FluentLocalisationError, FluentLocalisationSystem,
 };
 use hornbeam_interpreter::{InterpreterError, LoadedTemplates};
-use notify::Watcher;
 use std::convert::Infallible;
 use std::path::{Path, PathBuf};
 
@@ -23,7 +22,6 @@ pub use hornbeam_interpreter::Params;
 
 use crate::interpreted::hot_reload::start_hot_reloader;
 pub use lazy_static::lazy_static;
-use tokio::io;
 
 #[cfg(feature = "hot_reload")]
 pub mod hot_reload;
@@ -174,7 +172,7 @@ macro_rules! render_template_string {
         // TODO LOCALE
         {
             let manager = $manager.load();
-            let prepared = manager.prepare(stringify!($template_name), None, $crate::interpreter_params!{ $($params)* });
+            let prepared = manager.prepare(stringify!($template_name), None, $crate::interpreter_params!{ $($params)* }, $locale);
             let finished_string = prepared.render_to_string();
             if $crate::is_hot_reload_enabled() {
                 // Hacky, but inject the auto-hot-reloader into the page :P
diff --git a/hornbeam_interpreter/src/engine.rs b/hornbeam_interpreter/src/engine.rs
index b640246..28c2928 100644
--- a/hornbeam_interpreter/src/engine.rs
+++ b/hornbeam_interpreter/src/engine.rs
@@ -28,6 +28,7 @@ pub(crate) struct Interpreter<'a, O, LS> {
     pub(crate) program: &'a BTreeMap<String, Arc<Vec<Step>>>,
     pub(crate) output: O,
     pub(crate) localisation: Arc<LS>,
+    pub(crate) locale: String,
     pub(crate) scopes: Vec<Scope<'a>>,
 }
 
@@ -577,7 +578,7 @@ impl<'a, O: OutputSystem + Send, LS: LocalisationSystem + Sync + Send> Interpret
 
                 let localised_text = self
                     .localisation
-                    .lookup(trans_key, &parameters_evaluated)
+                    .lookup(trans_key, &parameters_evaluated, &self.locale)
                     .map_err(|underlying| InterpreterError::Localisation {
                         underlying,
                         trans_key: (trans_key as &str).to_owned(),
diff --git a/hornbeam_interpreter/src/interface.rs b/hornbeam_interpreter/src/interface.rs
index e87bbc3..92b0e3f 100644
--- a/hornbeam_interpreter/src/interface.rs
+++ b/hornbeam_interpreter/src/interface.rs
@@ -24,6 +24,7 @@ pub trait LocalisationSystem {
         &self,
         trans_key: &str,
         params: &BTreeMap<&str, Value>,
+        locale: &str,
     ) -> Result<Cow<str>, Self::Error>;
 }
 
@@ -148,6 +149,7 @@ impl<'a, LS> LoadedTemplates<LS> {
         template_name: &str,
         fragment_name: Option<&str>,
         params: Params,
+        locale: String,
     ) -> PreparedTemplate<LS> {
         PreparedTemplate {
             all_instructions: Arc::new(self.template_functions.clone()),
@@ -158,6 +160,7 @@ impl<'a, LS> LoadedTemplates<LS> {
             },
             variables: params,
             localisation: self.localisation.clone(),
+            locale,
         }
     }
 }
@@ -167,6 +170,7 @@ pub struct PreparedTemplate<LS> {
     pub(crate) entrypoint: String,
     pub(crate) variables: Params,
     pub(crate) localisation: Arc<LS>,
+    pub(crate) locale: String,
 }
 
 impl<LS: LocalisationSystem + Sync + Send> PreparedTemplate<LS> {
@@ -179,6 +183,7 @@ impl<LS: LocalisationSystem + Sync + Send> PreparedTemplate<LS> {
             program: &self.all_instructions,
             output,
             localisation: self.localisation,
+            locale: self.locale,
             scopes: vec![Scope {
                 variables: self.variables.params,
                 slots: Default::default(),
diff --git a/hornbeam_interpreter/src/localisation.rs b/hornbeam_interpreter/src/localisation.rs
index e15ea48..b2324c9 100644
--- a/hornbeam_interpreter/src/localisation.rs
+++ b/hornbeam_interpreter/src/localisation.rs
@@ -18,6 +18,7 @@ impl LocalisationSystem for NoLocalisation {
         &self,
         _trans_key: &str,
         _params: &BTreeMap<&str, Value>,
+        _locale: &str,
     ) -> Result<Cow<str>, Self::Error> {
         Err("No localisation support available.")
     }
@@ -34,6 +35,7 @@ impl LocalisationSystem for DebugLocalisationSystem {
         &self,
         trans_key: &str,
         params: &BTreeMap<&str, Value>,
+        _locale: &str,
     ) -> Result<Cow<str>, Self::Error> {
         Ok(Cow::from(format!("@{trans_key}{{{params:?}}}")))
     }
diff --git a/hornbeam_interpreter/src/localisation/fluent.rs b/hornbeam_interpreter/src/localisation/fluent.rs
index 73343b1..1649289 100644
--- a/hornbeam_interpreter/src/localisation/fluent.rs
+++ b/hornbeam_interpreter/src/localisation/fluent.rs
@@ -6,7 +6,6 @@ use crate::engine::Value;
 use crate::interface::LocalisationSystem;
 use fluent_templates::fluent_bundle::types::FluentNumber;
 use fluent_templates::fluent_bundle::FluentValue;
-use fluent_templates::loader::langid;
 use fluent_templates::{ArcLoader, LanguageIdentifier, Loader};
 use std::borrow::Cow;
 use std::collections::{BTreeMap, HashMap};
@@ -60,6 +59,9 @@ pub enum FluentLocalisationError {
     #[error("no translation found for {trans_key} in {lang_id}")]
     NoTranslation { trans_key: String, lang_id: String },
 
+    #[error("bad language ID {lang_id:?}")]
+    BadLocale { lang_id: String },
+
     #[error("can't convert param {param_name} of type {param_type} to a fluent type")]
     IncompatibleValue {
         param_name: String,
@@ -74,8 +76,14 @@ impl LocalisationSystem for FluentLocalisationSystem {
         &self,
         trans_key: &str,
         params: &BTreeMap<&str, Value>,
+        locale: &str,
     ) -> Result<Cow<str>, Self::Error> {
-        let li: LanguageIdentifier = langid!("en-GB"); // TODO get the language tag from somewhere
+        let li: LanguageIdentifier =
+            LanguageIdentifier::from_bytes(locale.as_bytes()).map_err(|_| {
+                FluentLocalisationError::BadLocale {
+                    lang_id: locale.to_owned(),
+                }
+            })?;
         let mut mapped_params = HashMap::with_capacity(params.len());
         for (&k, v) in params {
             if let Some(mapped_val) = interpreter_value_to_fluent_value(v) {