diff --git a/doc/MANUAL.md b/doc/MANUAL.md
index cc6ef31..525c4fc 100644
--- a/doc/MANUAL.md
+++ b/doc/MANUAL.md
@@ -242,6 +242,8 @@ FIXME
       client's browser. This allows you to output images, binary files, etc to
       the client. The script must include the proper headers and body itself. 
 
+**All output is assumed to be UTF8, regardless of system encoding!**
+
 If the script's exit code is 0, the output of the script (stdout) is captured
 and shown to the user in the browser.
 
diff --git a/src/scriptform.py b/src/scriptform.py
index b4f9fad..4f5e6e7 100755
--- a/src/scriptform.py
+++ b/src/scriptform.py
@@ -822,12 +822,12 @@ class ScriptFormWebApp(WebAppHandler):
             result = form_config.callback(form_name, form_values, self)
             if result:
                 if result['exitcode'] != 0:
-                    msg = u'<span class="error">{0}</span>'.format(cgi.escape(result['stderr']))
+                    msg = u'<span class="error">{0}</span>'.format(cgi.escape(result['stderr'].decode('utf8')))
                 else:
                     if form_def.output == 'escaped':
-                        msg = u'<pre>{0}</pre>'.format(cgi.escape(result['stdout']))
+                        msg = u'<pre>{0}</pre>'.format(cgi.escape(result['stdout'].decode('utf8')))
                     else:
-                        msg = result['stdout']
+                        msg = result['stdout'].decode('utf8')
 
                 output = html_submit_response.format(
                     header=html_header.format(title=form_config.title),