diff --git a/caldav/lib/error.py b/caldav/lib/error.py
index a63ec12a..b4a239dd 100644
--- a/caldav/lib/error.py
+++ b/caldav/lib/error.py
@@ -12,7 +12,8 @@
     ## The default debugmode should be PRODUCTION in official releases,
     ## and DEVELOPMENT when doing beta testing.
     ## TODO: find some way to automate this.
-    debugmode = 'DEVELOPMENT'
+    #debugmode = 'DEVELOPMENT'
+    debugmode = 'PRODUCTION'
 
 log = logging.getLogger('caldav')
 if debugmode.startswith('DEBUG'):
diff --git a/changelog-0.9.md b/changelog-0.9.md
index 7cb81ff4..0f5d740f 100644
--- a/changelog-0.9.md
+++ b/changelog-0.9.md
@@ -1,5 +1,10 @@
 # Changelog v0.9.0 -> v0.9.1
 
+## Quick summary
+
+* Tweaks to support the DAVMail server implementation
+* v0.9.0 broke for python 3.5 and lower, due to usage of fstrings.  v0.9.1 has been tested with python 3.5.
+
 ## Minor changes
 
 * Quite some users are complaining because recurring events aren't supported - which is intentional, because the server is supposed to take care of that.  Unfortunately quite some servers doesn't.  Thanks to cos, at least we now have some code in place to log an error (or optionally raising an error) when recurrences aren't taken care of (though, it only works if the server is returning non-expanded recurring events - if searching for a recurrence and the server doesn't find it, then ... no error logged).  The error message is referring to https://github.com/python-caldav/caldav/issues/157
diff --git a/setup.py b/setup.py
index 4de49dc6..a269d9ff 100755
--- a/setup.py
+++ b/setup.py
@@ -5,7 +5,7 @@
 
 ## ATTENTION! when doing releases, the default debugmode in lib/error.py should be set to PRODUCTION.
 ## (TODO: any nicer ways than doing this manually?  Make a "releases" branch, maybe?)
-version = '0.9.1dev'
+version = '0.9.1'
 
 if __name__ == '__main__':
     ## For python 2.7 and 3.5 we depend on pytz and tzlocal.  For 3.6 and up, batteries are included.  Same with mock. (But unfortunately the icalendar library only support pytz timezones, so we'll keep pytz around for a bit longer).