diff --git a/src/util.rs b/src/util.rs
index f8deaa40a2f5510dbb1ba4d1bbc3b33b93b863b7..2c47060c06d77e10bc2f0f8ea2e2df7f1de6dbe0 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -50,7 +50,7 @@ where
     S: AsRef<OsStr>,
     P: AsRef<Path>,
 {
-    let cargo = std::env::var("CARGO").unwrap_or("cargo".to_string());
+    let cargo = std::env::var("CARGO").unwrap_or_else(|_| "cargo".to_string());
     let mut cmd = Command::new(cargo);
     if let Some(path) = working_dir {
         log::debug!("Setting cargo working dir to '{}'", path.as_ref().display());