diff --git a/system_api_stub/Cargo.toml b/system_api_stub/Cargo.toml
index 764a68c7b1..d5a8ec1f35 100644
--- a/system_api_stub/Cargo.toml
+++ b/system_api_stub/Cargo.toml
@@ -2,7 +2,7 @@
 name = "system_api"
 version = "0.1.0"
 authors = ["The Chromium OS Authors"]
-edition = "2021"
+edition = "2018"
 
 [lib]
 path = "src/system_api.rs"