diff --git a/codex-rs/core/src/model_provider_info.rs b/codex-rs/core/src/model_provider_info.rs
index 887917f4..98f07deb 100644
--- a/codex-rs/core/src/model_provider_info.rs
+++ b/codex-rs/core/src/model_provider_info.rs
@@ -96,7 +96,7 @@ impl ModelProviderInfo {
         auth: &Option<CodexAuth>,
     ) -> crate::error::Result<reqwest::RequestBuilder> {
         let effective_auth = match self.api_key() {
-            Ok(Some(key)) => Some(CodexAuth::from_api_key(key)),
+            Ok(Some(key)) => Some(CodexAuth::from_api_key(&key)),
             Ok(None) => auth.clone(),
             Err(err) => {
                 if auth.is_some() {
diff --git a/codex-rs/core/tests/client.rs b/codex-rs/core/tests/client.rs
index 2ea772e3..bd7ad2fe 100644
--- a/codex-rs/core/tests/client.rs
+++ b/codex-rs/core/tests/client.rs
@@ -93,7 +93,7 @@ async fn includes_session_id_and_model_headers_in_request() {
     let ctrl_c = std::sync::Arc::new(tokio::sync::Notify::new());
     let CodexSpawnOk { codex, .. } = Codex::spawn(
         config,
-        Some(CodexAuth::from_api_key("Test API Key".to_string())),
+        Some(CodexAuth::from_api_key("Test API Key")),
         ctrl_c.clone(),
     )
     .await
@@ -167,7 +167,7 @@ async fn includes_base_instructions_override_in_request() {
     let ctrl_c = std::sync::Arc::new(tokio::sync::Notify::new());
     let CodexSpawnOk { codex, .. } = Codex::spawn(
         config,
-        Some(CodexAuth::from_api_key("Test API Key".to_string())),
+        Some(CodexAuth::from_api_key("Test API Key")),
         ctrl_c.clone(),
     )
     .await
@@ -226,7 +226,7 @@ async fn originator_config_override_is_used() {
     let ctrl_c = std::sync::Arc::new(tokio::sync::Notify::new());
     let CodexSpawnOk { codex, .. } = Codex::spawn(
         config,
-        Some(CodexAuth::from_api_key("Test API Key".to_string())),
+        Some(CodexAuth::from_api_key("Test API Key")),
         ctrl_c.clone(),
     )
     .await
@@ -364,7 +364,7 @@ async fn includes_user_instructions_message_in_request() {
     let ctrl_c = std::sync::Arc::new(tokio::sync::Notify::new());
     let CodexSpawnOk { codex, .. } = Codex::spawn(
         config,
-        Some(CodexAuth::from_api_key("Test API Key".to_string())),
+        Some(CodexAuth::from_api_key("Test API Key")),
         ctrl_c.clone(),
     )
     .await
diff --git a/codex-rs/core/tests/compact.rs b/codex-rs/core/tests/compact.rs
index bf47feed..fa5c81d8 100644
--- a/codex-rs/core/tests/compact.rs
+++ b/codex-rs/core/tests/compact.rs
@@ -145,7 +145,7 @@ async fn summarize_context_three_requests_and_instructions() {
     let ctrl_c = std::sync::Arc::new(tokio::sync::Notify::new());
     let CodexSpawnOk { codex, .. } = Codex::spawn(
         config,
-        Some(CodexAuth::from_api_key("dummy".to_string())),
+        Some(CodexAuth::from_api_key("dummy")),
         ctrl_c.clone(),
     )
     .await
diff --git a/codex-rs/core/tests/stream_no_completed.rs b/codex-rs/core/tests/stream_no_completed.rs
index 8a4216b1..0ded3337 100644
--- a/codex-rs/core/tests/stream_no_completed.rs
+++ b/codex-rs/core/tests/stream_no_completed.rs
@@ -99,7 +99,7 @@ async fn retries_on_early_close() {
     config.model_provider = model_provider;
     let CodexSpawnOk { codex, .. } = Codex::spawn(
         config,
-        Some(CodexAuth::from_api_key("Test API Key".to_string())),
+        Some(CodexAuth::from_api_key("Test API Key")),
         ctrl_c,
     )
     .await
diff --git a/codex-rs/login/src/lib.rs b/codex-rs/login/src/lib.rs
index 8c8ad75b..8571abcf 100644
--- a/codex-rs/login/src/lib.rs
+++ b/codex-rs/login/src/lib.rs
@@ -52,9 +52,9 @@ impl PartialEq for CodexAuth {
 }
 
 impl CodexAuth {
-    pub fn from_api_key(api_key: String) -> Self {
+    pub fn from_api_key(api_key: &str) -> Self {
         Self {
-            api_key: Some(api_key),
+            api_key: Some(api_key.to_owned()),
             mode: AuthMode::ApiKey,
             auth_file: PathBuf::new(),
             auth_dot_json: Arc::new(Mutex::new(None)),