diff --git a/misc/log-analytics/import_logs.py b/misc/log-analytics/import_logs.py
index fa95ebfbc5e142d0a158aaba640016ce3859256c..82f4449c7350fa5f7f55c8482b216b2dc8ca65ed 100755
--- a/misc/log-analytics/import_logs.py
+++ b/misc/log-analytics/import_logs.py
@@ -946,7 +946,7 @@ class Recorder(object):
         result = piwik.call_api(
             'CoreAdminHome.invalidateArchivedReports',
             dates=','.join(dates),
-            idSites=','.join(stats.piwik_sites),
+            idSites=','.join(str(site_id) for site_id in stats.piwik_sites),
         )