diff --git a/ext/csv.py b/ext/csv.py
index cdef3271..8fe43fc5 100755
--- a/ext/csv.py
+++ b/ext/csv.py
@@ -17,11 +17,10 @@ total_active_time = 0
 
 j = json.loads(doc)
 for object in j:
-    line = '"%s",' % object['start']
-    line += '"%s"' % (object['end'] if 'end' in object else '')
+    line = '"{}","{}"'.format(object['start'], (object['end'] if 'end' in object else ''))
 
     if 'tags' in object:
         for tag in object['tags']:
-            line += ',"%s"' % tag
+            line += ',"{}"'.format(tag)
 
     print(line)