diff --git a/src/util/sexpr/format.cpp b/src/util/sexpr/format.cpp
index 71d855e9de..ace9d25e98 100644
--- a/src/util/sexpr/format.cpp
+++ b/src/util/sexpr/format.cpp
@@ -225,8 +225,8 @@ int format::space_upto_line_break(sexpr const & s, int available, bool & found_n
         sexpr list  = sexpr_compose_list(s);
         int len = 0;
         while (!is_nil(list) && !found_newline) {
-            sexpr const & h = car(list);
-            list = cdr(list);
+            sexpr h = car(list);
+            list    = cdr(list);
             len += space_upto_line_break(h, available, found_newline);
             if (len > available)
                 throw space_exceeded();