diff --git a/codex-rs/core/src/config.rs b/codex-rs/core/src/config.rs
index 723ee5f8..f9c15b9e 100644
--- a/codex-rs/core/src/config.rs
+++ b/codex-rs/core/src/config.rs
@@ -9,7 +9,6 @@ use crate::config_types::ShellEnvironmentPolicy;
 use crate::config_types::ShellEnvironmentPolicyToml;
 use crate::config_types::Tui;
 use crate::config_types::UriBasedFileOpener;
-use crate::flags::OPENAI_DEFAULT_MODEL;
 use crate::model_family::ModelFamily;
 use crate::model_family::find_family_for_model;
 use crate::model_provider_info::ModelProviderInfo;
@@ -26,6 +25,8 @@ use tempfile::NamedTempFile;
 use toml::Value as TomlValue;
 use toml_edit::DocumentMut;
 
+const OPENAI_DEFAULT_MODEL: &str = "gpt-5";
+
 /// 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
 /// the context window.
diff --git a/codex-rs/core/src/flags.rs b/codex-rs/core/src/flags.rs
index c1504054..60201a3b 100644
--- a/codex-rs/core/src/flags.rs
+++ b/codex-rs/core/src/flags.rs
@@ -3,7 +3,6 @@ use std::time::Duration;
 use env_flags::env_flags;
 
 env_flags! {
-    pub OPENAI_DEFAULT_MODEL: &str = "codex-mini-latest";
     pub OPENAI_API_BASE: &str = "https://api.openai.com/v1";
 
     /// Fallback when the provider-specific key is not set.