diff --git a/codex-rs/core/tests/common/test_codex_exec.rs b/codex-rs/core/tests/common/test_codex_exec.rs
index 478d0c57f4..241226d950 100644
--- a/codex-rs/core/tests/common/test_codex_exec.rs
+++ b/codex-rs/core/tests/common/test_codex_exec.rs
@@ -15,7 +15,8 @@ impl TestCodexExecBuilder {
             .expect("should find binary for codex-exec");
         cmd.current_dir(self.cwd.path())
             .env("CODEX_HOME", self.home.path())
-            .env(CODEX_API_KEY_ENV_VAR, "dummy");
+            .env(CODEX_API_KEY_ENV_VAR, "dummy")
+            .arg("--custom-apply-patch");
         cmd
     }
     pub fn cmd_with_server(&self, server: &MockServer) -> assert_cmd::Command {