diff --git a/scheme/httpd/handlers.scm b/scheme/httpd/handlers.scm
index 0b29ac9..81bdeaa 100644
--- a/scheme/httpd/handlers.scm
+++ b/scheme/httpd/handlers.scm
@@ -51,11 +51,20 @@
      (string=? hostname (string-trim (get-header (request-headers req) 'host))))
    handler default-handler))
 
+(define (get-header headers tag)
+  (cond
+   ((assq tag headers) => cdr)
+   (else
+    (http-error (status-code bad-request) #f
+		(string-append "Request did not contain "
+			       (symbol->string tag)
+			       " header")))))
+
 ;; selects handler according to path-prefix
 ;; if path-prefix matches, handler is called without the path-prefix
 (define (make-path-prefix-handler path-prefix handler default-handler)
   (lambda (path req)
-    (if (string=? path-prefix (car path))
+    (if (and (pair? path) (string=? path-prefix (car path)))
 	(handler (cdr path) req)
 	(default-handler path req))))