diff --git a/pywb/recorder/multifilewarcwriter.py b/pywb/recorder/multifilewarcwriter.py
index 5d0ec1eb3..d612198be 100644
--- a/pywb/recorder/multifilewarcwriter.py
+++ b/pywb/recorder/multifilewarcwriter.py
@@ -32,6 +32,7 @@ def __init__(self, dir_template, filename_template=None, max_size=0,
         self.dedup_index = kwargs.get('dedup_index')
         self.dedup_by_url = kwargs.get('dedup_by_url')
         self.filename_template = filename_template
+        self.gzip = self.filename_template.endswith(".gz")
         self.max_size = max_size
         if max_idle_secs > 0:
             self.max_idle_time = datetime.timedelta(seconds=max_idle_secs)