diff --git a/crates/macro/src/lib.rs b/crates/macro/src/lib.rs
index 49470cf..d8b2ae3 100644
--- a/crates/macro/src/lib.rs
+++ b/crates/macro/src/lib.rs
@@ -324,6 +324,8 @@ fn generate_code(
     quote! {
         use rust_i18n::{BackendExt, CowStr, MinifyKey};
         use std::borrow::Cow;
+        use std::sync::Mutex;
+        use rust_i18n::once_cell::sync::Lazy;
 
         /// I18n backend instance
         ///
@@ -334,11 +336,17 @@ fn generate_code(
             #(#all_translations)*
             #extend_code
 
-            #default_locale
+            if *_RUST_I18N_INITIALIZED_DEFAULT_LOCALE.lock().unwrap() == false {
+                *_RUST_I18N_INITIALIZED_DEFAULT_LOCALE.lock().unwrap() = true;
+                #default_locale
+            }
 
             Box::new(backend)
         });
 
+        /// To mark the default locale has been initialized
+        static _RUST_I18N_INITIALIZED_DEFAULT_LOCALE: Lazy<Mutex<bool>> = Lazy::new(|| Mutex::new(false));
+
         static _RUST_I18N_FALLBACK_LOCALE: Option<&[&'static str]> = #fallback;
         static _RUST_I18N_MINIFY_KEY: bool = #minify_key;
         static _RUST_I18N_MINIFY_KEY_LEN: usize = #minify_key_len;
diff --git a/crates/support/src/backend.rs b/crates/support/src/backend.rs
index 54fd031..ff9c38a 100644
--- a/crates/support/src/backend.rs
+++ b/crates/support/src/backend.rs
@@ -74,10 +74,7 @@ impl SimpleBackend {
             .map(|(k, v)| ((*k).into(), (*v).into()))
             .collect::<HashMap<_, _>>();
 
-        let trs = self
-            .translations
-            .entry(locale.into())
-            .or_insert(HashMap::new());
+        let trs = self.translations.entry(locale.into()).or_default();
         trs.extend(data);
     }
 }
diff --git a/tests/integration_tests.rs b/tests/integration_tests.rs
index 9e88084..18fbd9f 100644
--- a/tests/integration_tests.rs
+++ b/tests/integration_tests.rs
@@ -315,4 +315,12 @@ mod tests {
             "This is missing key fallbacked to en."
         );
     }
+
+    #[test]
+    fn test_set_locale() {
+        rust_i18n::set_locale("zh-CN");
+        for _ in 0..5 {
+            assert_eq!(t!("hello"), "Bar - 你好世界！");
+        }
+    }
 }