diff --git a/build.rs b/build.rs
index 98b7bc7..9b804c9 100644
--- a/build.rs
+++ b/build.rs
@@ -26,7 +26,7 @@ fn main() {
                 dir_entry.file_type().is_file()
                     && Path::new(dir_entry.file_name())
                         .extension()
-                        .map(|ext| ext.to_ascii_lowercase() == "org")
+                        .map(|ext| ext.eq_ignore_ascii_case("org"))
                         .unwrap_or(false)
             }
             Err(_) => true,