diff --git a/src/librustdoc/html/format.rs b/src/librustdoc/html/format.rs
index 092e1548446..6d96b172a2e 100644
--- a/src/librustdoc/html/format.rs
+++ b/src/librustdoc/html/format.rs
@@ -205,7 +205,7 @@ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
             }
         }
         if !f.alternate() {
-            f.write_str("</span>")?;
+            clause.push_str("</span>");
             let plain = format!("{:#}", self);
             if plain.len() > 80 {
                 let padding = repeat("&nbsp;").take(8).collect::<String>();