diff --git a/pitfall/pitfall/parse.rkt b/pitfall/pitfall/parse.rkt
index 78bb3851..90e19d4f 100644
--- a/pitfall/pitfall/parse.rkt
+++ b/pitfall/pitfall/parse.rkt
@@ -50,17 +50,17 @@
                                                                            [("f") "\f"]
                                                                            [else sub])))]
             [str (regexp-replace* @pregexp{\\(\d{2,3})} str (λ (m sub) (string (integer->char (string->number sub 8)))))])
-       str)]))
+       (co-string str))]))
 
 (module+ test
-  (check-equal? @pf-string{(Testing)} "Testing")
+  (check-equal? @pf-string{(Testing)} (co-string "Testing"))
   (check-equal? (pf-string @string-append{(Test\
- ing)}) "Testing")
-  (check-equal? @pf-string{(Test\)ing)} "Test)ing")
-  (check-equal? @pf-string{(Test\ning)} "Test\ning")
-  (check-equal? @pf-string{(Test\\ing)} "Test\\ing")
-  (check-equal? @pf-string{(A\53B)} "A+B")
-  (check-equal? @pf-string{(A\053B)} "A+B")
+ ing)}) (co-string "Testing"))
+  (check-equal? @pf-string{(Test\)ing)} (co-string "Test)ing"))
+  (check-equal? @pf-string{(Test\ning)} (co-string "Test\ning"))
+  (check-equal? @pf-string{(Test\\ing)} (co-string "Test\\ing"))
+  (check-equal? @pf-string{(A\53B)} (co-string "A+B"))
+  (check-equal? @pf-string{(A\053B)} (co-string "A+B"))
   #;(check-equal? @pf-string{(D:19990209153925-08\'00\')})
   #;(check-true (andmap byte? @pf-string{<1C2D3F>}))
   #;(check-true (andmap byte? @pf-string{<1C 2D 3F>})))
diff --git a/pitfall/pitfall/render.rkt b/pitfall/pitfall/render.rkt
index 987c1b44..f7aff82a 100644
--- a/pitfall/pitfall/render.rkt
+++ b/pitfall/pitfall/render.rkt
@@ -34,7 +34,7 @@
        (if (co-io? cosexpr)
            (cons (cons (co-io-idx cosexpr) offset) io-locs)
            io-locs))))
-  (define header-str (cosexpr->bytes (co-header "%PDF-1.3\n%¥±ë")))
+  (define header-str (cosexpr->bytes (co-header "%PDF-1.4\n%¥±ë")))
   (define trailer-str (cosexpr->bytes
                        (co-trailer (co-dict (hasheq 'Size (length bstrs) 'Root (co-io-ref 1 0))))))
   (define last-offset (for/sum ([bstr (in-list bstrs)])
@@ -78,6 +78,7 @@
           >>}]
         [(co-io-ref? x)
          @string-append{@(loop (co-io-ref-idx x)) @(loop (co-io-ref-rev x)) R}]
+        [(co-string? x) (format "(~a)" (co-string-string x))]
         [(co-stream? x)
          @string-append{
           @(loop (co-stream-dict x))
@@ -120,4 +121,6 @@
   (co-dict (apply hasheq xs)))
 
 (define (make-co-stream bstr)
-  (co-stream  (make-co-dict 'Length (bytes-length bstr)) bstr))
\ No newline at end of file
+  (co-stream  (make-co-dict 'Length (bytes-length bstr)) bstr))
+
+(cosexpr->bytes (make-co-dict 'Hello (co-string "World")))
\ No newline at end of file
diff --git a/pitfall/pitfall/struct.rkt b/pitfall/pitfall/struct.rkt
index 9b141a9c..d0a1b449 100644
--- a/pitfall/pitfall/struct.rkt
+++ b/pitfall/pitfall/struct.rkt
@@ -6,7 +6,8 @@
 (struct co-stream (dict data) #:transparent)
 (struct co-version (num) #:transparent)
 (struct co-header (string) #:transparent)
+(struct co-string (string) #:transparent)
 (struct co-io (idx rev thing) #:transparent)
 (struct co-io-ref (idx rev) #:transparent)
 (struct co-comment (text) #:transparent)
-(struct co-trailer (dict) #:transparent)
\ No newline at end of file
+(struct co-trailer (dict) #:transparent)