diff --git a/scheme/httpd/seval.scm b/scheme/httpd/seval.scm
index 72cbf0a..aa47f7b 100644
--- a/scheme/httpd/seval.scm
+++ b/scheme/httpd/seval.scm
@@ -9,10 +9,6 @@
 ;;; This is really just an handler example demonstrating how to upload code 
 ;;; into the server.
 
-;;; Besides, this handler has always been broken because it makes use
-;;; of the concept of http-reader-writer-body which is broken
-;;; itself. See response.scm.
-
 ;;; (do/timeout secs thunk)
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;; Run THUNK, and gun it down if it hasn't finished in SECS seconds.
@@ -51,75 +47,48 @@
 
 
 (define (seval path req)
-  (let ((body-length (get-body-length-from-content-length req))) ;;make sure we have a valid Content-length header in request
+  (let* ((message-body (read-message-body req))
+	(sexp (parse-request-sexp message-body)))
     (make-response
      (status-code ok)
      #f
      (time)
      "text/html"
      '()
-     (make-reader-writer-body ;; see response.scm for an explanation why the concept of http-reader-writer-body doesn't work
-      (lambda (iport oport options)
-	(with-fatal-error-handler
-
-	 (lambda (c decline)
-	   ;; no matter what kind of error (might be a server internal error), we emit this webpage:
-	   (emit-prolog oport)
-	   (with-tag oport html (xmlnsdecl-attr)		    
-		     (newline oport)
-		     (with-tag oport head ()
-			       (newline oport)
-			       (emit-title oport "No Program")
-			      (newline oport))
-		     (newline oport)
-		     (with-tag oport body ()
-			      (newline oport)
-			      (emit-header oport 1 "No Program")
-			      (newline oport)
-			      (with-tag oport p ()
-					(display
-					 "No program was found in the body of the request. 
-The request's body must be form-url encoded and contain a \"program=<sexp>\" pair." 
-					 oport)
-					(newline oport))
-			      (newline oport))
-		     (newline oport)))
-
-	 (let ((sexp (read-request-sexp body-length iport))) 
-	   (http-syslog (syslog-level debug) "read sexp: ~a" sexp)
-	   (emit-prolog oport)
-	   (with-tag oport html (xmlnsdecl-attr)
-		     (newline oport)
-		     (with-tag oport head ()
-			       (newline oport)
-			       (emit-title oport "Scheme program output")
-			       (newline oport))
-		     (newline oport)
-		     
-		     (with-tag oport body ()
-			       (newline oport)
-			       (do/timeout 
-				10
-				(receive vals
-					 ;; Do the computation.
-					 (begin (emit-header oport 1 "Output from execution")
-						(newline oport)
-						(with-tag oport pre ()
-							  (newline oport)
-							  (force-output oport); In case we're gunned down.
-							  (with-current-output-port oport
-										    (eval-safely sexp))))
-					 
-					 ;; Pretty-print the returned value(s).;; hier noch mal newline rausschreiben?
-					 (emit-header oport 1 "Return value(s)")
-					 (with-tag oport pre ()
-						   (for-each (lambda (val) (p val oport))
-							     vals)))))))))))))
+     (make-writer-body
+      (lambda (oport options)
+	(http-syslog (syslog-level debug) "read sexp: ~a" sexp)
+	(emit-prolog oport)
+	(with-tag oport html (xmlnsdecl-attr)
+		  (newline oport)
+		  (with-tag oport head ()
+			    (newline oport)
+			    (emit-title oport "Scheme program output")
+			    (newline oport))
+		  (newline oport)
+		  
+		  (with-tag oport body ()
+			    (newline oport)
+			    (do/timeout 
+			     10
+			     (receive vals
+				      ;; Do the computation.
+				      (begin (emit-header oport 1 "Output from execution")
+					     (newline oport)
+					     (with-tag oport pre ()
+						       (newline oport)
+						       (force-output oport); In case we're gunned down.
+						       (with-current-output-port oport
+										 (eval-safely sexp))))
+				      
+				      ;; Pretty-print the returned value(s).;; hier noch mal newline rausschreiben?
+				      (emit-header oport 1 "Return value(s)")
+				      (with-tag oport pre ()
+						(for-each (lambda (val) (p val oport))
+							  vals)))))))))))
 
 
-;;; Read an HTTP request entity body from stdin. The Content-length:
-;;; entity-header field of request REQ tells how many bytes this entity
-;;; is. 
+;;; Parse the request's message body.
 
 ;;; We assume, that the entity is "form-url encoded" data (see
 ;;; parse-forms.scm for a description of this encoding). This
@@ -129,12 +98,13 @@ The request's body must be form-url encoded and contain a \"program=<sexp>\" pai
 ;;; Pull out the program=<stuff> string, extract <stuff>, 
 ;;; parse that into an s-expression, and return it.
 
-(define (read-request-sexp bytes iport)
-  (let* 
-      ((body (read-string bytes iport))   ;;read in bytes chars
-       (parsed-html-form-query (parse-html-form-query body)) ;; and parse them up.
-       (program (cond ((assoc "program" parsed-html-form-query) => cdr)
-		      (else (error "No program in entity body.")))))
+(define (parse-request-sexp body)
+  (let* ((parsed-html-form-query (parse-html-form-query body))
+	 (program (cond ((assoc "program" parsed-html-form-query) => cdr)
+		      (else (fatal-syntax-error "No program was found in request's message body.")))))
     (http-syslog (syslog-level debug)
 		 "Seval sexp: ~s" program)
-    (read (make-string-input-port program)))) ;; return first sexp, discard others
+    (with-fatal-error-handler 
+     (lambda (c decline)
+       (fatal-syntax-error "The program in the request's message body isn't a valid s-expression"))
+     (read (make-string-input-port program))))) ;; return first sexp, discard others