diff --git a/src/main.lisp b/src/main.lisp
index f5a5b53..839dc49 100644
--- a/src/main.lisp
+++ b/src/main.lisp
@@ -11,7 +11,8 @@
                 #:parse)
   (:import-from #:dexador
                 #:request
-                #:http-request-failed)
+                #:http-request-failed
+                #:response-status)
   (:import-from #:quri
                 #:make-uri
                 #:render-uri)
@@ -26,30 +27,31 @@
 (defparameter *api-key* nil)
 (defparameter *service-domain* nil)
 
-(defun %request (method endpoint &optional (path "") (query nil) (content nil))
+(defun %request (method endpoint &optional path query content)
+  (or *service-domain* (error "microcms:*service-domain* is not configured."))
+  (or *api-key* (error "microcms:*api-key* is not configured."))
   (let* ((url (%build-uri endpoint path query))
-         (headers `(("X-MICROCMS-API-KEY" . ,*api-key*)
-                    ("Content-Type" . "application/json"))))
-    (format t "API request url: ~a~%" url)
+         (req-headers `(("X-MICROCMS-API-KEY" . ,*api-key*)
+                        ("Content-Type" . "application/json"))))
     (handler-case
-        (multiple-value-bind (res-body status resp-headers)
+        (multiple-value-bind (res-body status res-headers)
             (request url
                      :method method
-                     :headers headers
+                     :headers req-headers
                      :content (and content (to-json content))
                      :force-binary nil)
-          (format t "API response status: ~a~%" status)
+          (format t "microCMS status: ~D~%" status)
           (when (and (stringp res-body)
-                     (search "application/json" (gethash "content-type" resp-headers)))
+                     (search "application/json" (gethash "content-type" res-headers)))
             (parse res-body)))
-      (http-request-failed ()
-        '(:|error| "API request failed")))))
+      (http-request-failed (e)
+        (format *error-output* "microCMS status: ~D~%" (response-status e))))))
 
-(defun %build-uri (endpoint &optional (path "") (query nil))
+(defun %build-uri (endpoint &optional path query)
   (let ((uri (make-uri
               :scheme "https"
               :host (format nil "~A.microcms.io" *service-domain*)
-              :path (format nil "/api/v1/~A/~A" endpoint path)
+              :path (format nil "/api/v1/~A~@[/~A~]" endpoint path)
               :query (%build-query query))))
     (render-uri uri)))