diff --git a/codex-rs/core/src/model_family.rs b/codex-rs/core/src/model_family.rs
index 5c5045fe4..3ed5fa299 100644
--- a/codex-rs/core/src/model_family.rs
+++ b/codex-rs/core/src/model_family.rs
@@ -12,7 +12,6 @@ const BASE_INSTRUCTIONS: &str = include_str!("../prompt.md");
 
 const GPT_5_CODEX_INSTRUCTIONS: &str = include_str!("../gpt_5_codex_prompt.md");
 const GPT_5_1_INSTRUCTIONS: &str = include_str!("../gpt_5_1_prompt.md");
-const GPT_5_1_CODEX_MAX_INSTRUCTIONS: &str = include_str!("../gpt-5.1-codex-max_prompt.md");
 
 /// A model family is a group of models that share certain characteristics.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]