diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index cc5cdf9f4e7..c8e09629f92 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -123,7 +123,7 @@ struct Output {
 }
 
 pub fn main() {
-    const STACK_SIZE: usize = 32000000; // 32MB
+    const STACK_SIZE: usize = 32_000_000; // 32MB
     let res = std::thread::Builder::new().stack_size(STACK_SIZE).spawn(move || {
         let s = env::args().collect::<Vec<_>>();
         main_args(&s)