diff --git a/src/rustbook/build.rs b/src/rustbook/build.rs
index dc97d1e24349..69ef20884f4a 100644
--- a/src/rustbook/build.rs
+++ b/src/rustbook/build.rs
@@ -145,7 +145,8 @@ fn render(book: &Book, tgt: &Path) -> CliResult<()> {
             format!("--html-after-content={}", postlude.display()),
             format!("--markdown-playground-url=http://play.rust-lang.org"),
             format!("--markdown-css={}", item.path_to_root.join("rust-book.css").display()),
-            format!("--markdown-css=http://fonts.googleapis.com/css?family&#61;Open+Sans:400italic,700italic,400,700"),
+            format!("--markdown-css={}",
+            "http://fonts.googleapis.com/css?family&#61;Open+Sans:400italic,700italic,400,700"),
             "--markdown-no-toc".to_string(),
         ];
         let output_result = rustdoc::main_args(rustdoc_args);