diff --git a/extra/parser-combinators/parser-combinators.factor b/extra/parser-combinators/parser-combinators.factor
index cdf89e1f37..bf06708e09 100755
--- a/extra/parser-combinators/parser-combinators.factor
+++ b/extra/parser-combinators/parser-combinators.factor
@@ -2,7 +2,7 @@
 ! See http://factorcode.org/license.txt for BSD license.
 USING: lazy-lists promises kernel sequences strings math
 arrays splitting quotations combinators namespaces
-unicode.case unicode.categories ;
+unicode.case unicode.categories sequences.deep ;
 IN: parser-combinators
 
 ! Parser combinator protocol
@@ -329,11 +329,6 @@ LAZY: <(+)> ( parser -- parser )
 LAZY: surrounded-by ( parser start end -- parser' )
     [ token ] 2apply swapd pack ;
 
-: flatten* ( obj -- )
-    dup array? [ [ flatten* ] each ] [ , ] if ;
-
-: flatten [ flatten* ] { } make ;
-
 : exactly-n ( parser n -- parser' )
     swap <repetition> <and-parser> [ flatten ] <@ ;