diff --git a/src/factor/build.rs b/src/factor/build.rs
index ba9ac6f19..ba65c01ae 100644
--- a/src/factor/build.rs
+++ b/src/factor/build.rs
@@ -82,7 +82,7 @@ fn main() {
     let n = args()
         .skip(1)
         .next()
-        .unwrap_or("1027".to_string())
+        .unwrap_or_else(|| "1027".to_string())
         .parse::<usize>()
         .ok()
         .unwrap_or(1027);
diff --git a/src/stdbuf/build.rs b/src/stdbuf/build.rs
index 256592301..73189508b 100644
--- a/src/stdbuf/build.rs
+++ b/src/stdbuf/build.rs
@@ -30,7 +30,7 @@ fn main() {
     let libstdbuf = format!(
         "{}/../../{}/{}/deps/liblibstdbuf{}",
         manifest_dir,
-        env::var("CARGO_TARGET_DIR").unwrap_or("target".to_string()),
+        env::var("CARGO_TARGET_DIR").unwrap_or_else(|_| "target".to_string()),
         profile,
         platform::DYLIB_EXT
     );