diff --git a/src/page-wiki.rkt b/src/page-wiki.rkt
index 82956e4..707157a 100644
--- a/src/page-wiki.rkt
+++ b/src/page-wiki.rkt
@@ -96,17 +96,20 @@
              (easy:response-body dest-res)))]))
 
 (define (page-wiki-with-data req)
-  (define post-data/bytes (request-post-data/raw req))
-  (define post-data/string (bytes->string/utf-8 post-data/bytes))
-  (define post-data (string->jsexpr post-data/string))
-  (define wikiname (jp "/wikiname" post-data))
-  (define path (jp "/path" post-data))
-  (take-json-rewrite-and-return-page
-   #:req req
-   #:wikiname wikiname
-   #:source-url (format "https://~a.fandom.com/wiki/~a" wikiname path)
-   #:data (jp "/data" post-data)
-   #:siteinfo (data->siteinfo (jp "/siteinfo" post-data))))
+  (response-handler
+   (define post-data/bytes (request-post-data/raw req))
+   (when (not post-data/bytes)
+     (raise-user-error 'page-wiki-with-data "POST requests only, please."))
+   (define post-data/string (bytes->string/utf-8 post-data/bytes))
+   (define post-data (string->jsexpr post-data/string))
+   (define wikiname (jp "/wikiname" post-data))
+   (define path (jp "/path" post-data))
+   (take-json-rewrite-and-return-page
+    #:req req
+    #:wikiname wikiname
+    #:source-url (format "https://~a.fandom.com/wiki/~a" wikiname path)
+    #:data (jp "/data" post-data)
+    #:siteinfo (data->siteinfo (jp "/siteinfo" post-data)))))
 
 (define (take-json-rewrite-and-return-page #:req req #:wikiname wikiname #:source-url source-url #:data data #:siteinfo siteinfo)
   (define title (jp "/parse/title" data ""))