diff --git a/codex-rs/Cargo.lock b/codex-rs/Cargo.lock
index 6359089371..88318a0b27 100644
--- a/codex-rs/Cargo.lock
+++ b/codex-rs/Cargo.lock
@@ -4261,6 +4261,7 @@ dependencies = [
  "reqwest",
  "serde_json",
  "shlex",
+ "similar",
  "tempfile",
  "tokio",
  "tokio-tungstenite",
diff --git a/codex-rs/core/tests/common/Cargo.toml b/codex-rs/core/tests/common/Cargo.toml
index c59edf57a6..8c1a79f02d 100644
--- a/codex-rs/core/tests/common/Cargo.toml
+++ b/codex-rs/core/tests/common/Cargo.toml
@@ -33,6 +33,7 @@ opentelemetry = { workspace = true }
 opentelemetry_sdk = { workspace = true }
 regex-lite = { workspace = true }
 serde_json = { workspace = true }
+similar = { workspace = true }
 tempfile = { workspace = true }
 tokio = { workspace = true, features = ["net", "time"] }
 tokio-tungstenite = { workspace = true }