diff --git a/payment_paypal/indico_payment_paypal/plugin.py b/payment_paypal/indico_payment_paypal/plugin.py
index 8e7764f..2dd06de 100644
--- a/payment_paypal/indico_payment_paypal/plugin.py
+++ b/payment_paypal/indico_payment_paypal/plugin.py
@@ -16,7 +16,7 @@ from wtforms.validators import DataRequired, Optional
 from indico.core.plugins import IndicoPlugin, url_for_plugin
 from indico.modules.events.payment import (PaymentEventSettingsFormBase, PaymentPluginMixin,
                                            PaymentPluginSettingsFormBase)
-from indico.util.string import remove_accents, unicode_to_ascii
+from indico.util.string import remove_accents, str_to_ascii
 from indico.web.forms.validators import UsedIf
 
 from indico_payment_paypal import _
@@ -67,8 +67,8 @@ class PaypalPaymentPlugin(PaymentPluginMixin, IndicoPlugin):
         event = data['event']
         registration = data['registration']
         data['item_name'] = '{}: registration for {}'.format(
-            unicode_to_ascii(remove_accents(registration.full_name, reencode=False)),
-            unicode_to_ascii(remove_accents(event.title, reencode=False))
+            str_to_ascii(remove_accents(registration.full_name, reencode=False)),
+            str_to_ascii(remove_accents(event.title, reencode=False))
         )
         data['return_url'] = url_for_plugin('payment_paypal.success', registration.locator.uuid, _external=True)
         data['cancel_url'] = url_for_plugin('payment_paypal.cancel', registration.locator.uuid, _external=True)
diff --git a/piwik/indico_piwik/reports.py b/piwik/indico_piwik/reports.py
index bbc8343..1499dc9 100644
--- a/piwik/indico_piwik/reports.py
+++ b/piwik/indico_piwik/reports.py
@@ -16,7 +16,6 @@ from indico.modules.events import Event
 from indico.modules.events.contributions import Contribution
 from indico.util.date_time import format_time, now_utc, utc_to_server
 from indico.util.serializer import Serializer
-from indico.util.string import to_unicode
 
 from indico_piwik.queries.graphs import PiwikQueryReportEventGraphCountries, PiwikQueryReportEventGraphDevices
 from indico_piwik.queries.metrics import (PiwikQueryReportEventMetricDownloads,
@@ -131,8 +130,7 @@ class ReportGeneral(ReportBase):
             cid = (contribution.legacy_mapping.legacy_contribution_id if contribution.legacy_mapping
                    else contribution.id)
             key = '{}t{}'.format(contribution.event_id, cid)
-            self.contributions[key] = u'{} ({})'.format(contribution.title,
-                                                        to_unicode(format_time(contribution.start_dt)))
+            self.contributions[key] = u'{} ({})'.format(contribution.title, format_time(contribution.start_dt))
 
 
 class ReportMaterial(ReportBase):