diff --git a/swh/journal/backfill.py b/swh/journal/backfill.py
--- a/swh/journal/backfill.py
+++ b/swh/journal/backfill.py
@@ -368,6 +368,13 @@
             yield record
 
 
+def _format_range_bound(bound):
+    if isinstance(bound, bytes):
+        return bound.hex()
+    else:
+        return str(bound)
+
+
 MANDATORY_KEYS = ['brokers', 'storage_dbconn', 'prefix', 'client_id']
 
 
@@ -438,7 +445,8 @@
         for range_start, range_end in RANGE_GENERATORS[object_type](
                 start_object, end_object):
             logger.info('Processing %s range %s to %s', object_type,
-                        range_start, range_end)
+                        _format_range_bound(range_start),
+                        _format_range_bound(range_end))
 
             for obj in fetch(
                 db, object_type, start=range_start, end=range_end,