diff --git a/response.lisp b/response.lisp
index ec84b98..987ffb2 100644
--- a/response.lisp
+++ b/response.lisp
@@ -78,7 +78,7 @@
 
 (defgeneric content-length (response)
   (:method (response)
-    (parse-integer (bvalue :content-length (http-headers response)))))
+    (parse-integer (drakma:header-value :content-length (http-headers response)))))
 
 (defgeneric specialize-response (response)
   (:method ((response response))