diff --git a/4chan_x.user.js b/4chan_x.user.js
index 69534dd96..194f39ca3 100644
--- a/4chan_x.user.js
+++ b/4chan_x.user.js
@@ -1853,7 +1853,7 @@
           for (name in data) {
             val = data[name];
             if (val) {
-              parts.push('Content-Disposition: form-data; name="' + name + '"\r\n\r\n' + toUTF8(val) + '\r\n');
+              parts.push('Content-Disposition: form-data; name="' + name + '"\r\n\r\n' + toUTF8(String(val)) + '\r\n');
             }
           }
           form = '--' + boundary + '\r\n' + parts.join('--' + boundary + '\r\n') + '--' + boundary + '--\r\n';
diff --git a/script.coffee b/script.coffee
index 4deff69b9..25eae008e 100644
--- a/script.coffee
+++ b/script.coffee
@@ -1419,7 +1419,7 @@ qr =
         delete data.upfile
 
         for name, val of data
-          parts.push 'Content-Disposition: form-data; name="' + name + '"\r\n\r\n' + toUTF8(val) + '\r\n' if val
+          parts.push 'Content-Disposition: form-data; name="' + name + '"\r\n\r\n' + toUTF8(String val) + '\r\n' if val
         form = '--' + boundary + '\r\n' + parts.join('--' + boundary + '\r\n') + '--' + boundary + '--\r\n'
 
       else