diff --git a/codex-rs/core/src/compact.rs b/codex-rs/core/src/compact.rs
index 10404dc6f2..1a90b7b223 100644
--- a/codex-rs/core/src/compact.rs
+++ b/codex-rs/core/src/compact.rs
@@ -30,7 +30,7 @@ use tracing::error;
 
 pub const SUMMARIZATION_PROMPT: &str = include_str!("../templates/compact/prompt.md");
 pub const SUMMARY_PREFIX: &str = include_str!("../templates/compact/summary_prefix.md");
-const COMPACT_USER_MESSAGE_MAX_TOKENS: usize = 20_001;
+const COMPACT_USER_MESSAGE_MAX_TOKENS: usize = 20_000;
 
 pub(crate) fn should_use_remote_compact_task(
     session: &Session,