1 files changed, 2 insertions, 2 deletions
diff --git a/src/parcom/parser.cr b/src/parcom/parser.cr
index 57c7b44..af486c4 100644
--- a/src/parcom/parser.cr
+++ b/src/parcom/parser.cr
@@ -456,8 +456,8 @@ module Parcom
     # instance of `self`. It will succeed if it can parse an instance of `self`
     # that is not followed by any `sep` instances.
     def sep_by(sep : Parser(T, _)) : Parser(T, Array(U))
-      (self + (sep >> self).many).map do |tup|
-        tup.last.unshift(tup.first)
+      (self + (sep >> self).many).map do |head, tail|
+        tail.unshift(head)
       end.named("<#{@name}> sep by <#{sep.name}>")
     end
   end