diff --git a/codex-rs/core/src/config.rs b/codex-rs/core/src/config.rs
index 8be93f76..48624ffc 100644
--- a/codex-rs/core/src/config.rs
+++ b/codex-rs/core/src/config.rs
@@ -32,7 +32,7 @@ use toml::Value as TomlValue;
 use toml_edit::DocumentMut;
 
 const OPENAI_DEFAULT_MODEL: &str = "gpt-5";
-pub const GPT5_HIGH_MODEL: &str = "gpt-5-high";
+pub const GPT5_HIGH_MODEL: &str = "gpt-5-high-new";
 
 /// Maximum number of bytes of the documentation that will be embedded. Larger
 /// files are *silently truncated* to this size so we do not take up too much of
diff --git a/codex-rs/tui/src/lib.rs b/codex-rs/tui/src/lib.rs
index 7ce17528..41e36a9c 100644
--- a/codex-rs/tui/src/lib.rs
+++ b/codex-rs/tui/src/lib.rs
@@ -380,11 +380,12 @@ async fn run_ratatui_app(
 
         if switch_to_new_model {
             config.model = GPT5_HIGH_MODEL.to_owned();
+            config.model_reasoning_effort = None;
             if let Err(e) = persist_model_selection(
                 &config.codex_home,
                 active_profile.as_deref(),
                 &config.model,
-                None,
+                config.model_reasoning_effort,
             )
             .await
             {