diff --git a/src/comp/syntax/print/pprust.rs b/src/comp/syntax/print/pprust.rs
index 8b1fa025cac0316fbf811258401207778b552b67..129d00f0f88603245187a39408c65344777f6f8c 100644
--- a/src/comp/syntax/print/pprust.rs
+++ b/src/comp/syntax/print/pprust.rs
@@ -1149,7 +1149,7 @@ fn print_arg(s: ps, x: ast::arg) {
           ast::return_ref(mut, arg) {
             word(s.s, mut ? "&!" : "&");
             if vec::len(decl.inputs) > 1u {
-                word(s.s, std::uint::str(arg));
+                word_space(s, std::uint::str(arg));
             }
           }
           _ {}