diff --git a/README.md b/README.md
index 29f23f74..2e357831 100644
--- a/README.md
+++ b/README.md
@@ -26,7 +26,7 @@
 <hr/>
 </div>
 
-ArchiveBox is a powerful self-hosted internet archiving solution written in Python 3. You feed it URLs of pages you want to archive, and it saves them to disk in a varitety of formats depending on the configuration and the content it detects.
+ArchiveBox is a powerful self-hosted internet archiving solution written in Python 3. You feed it URLs of pages you want to archive, and it saves them to disk in a variety of formats depending on the configuration and the content it detects.
 
 Your archive can be managed through the command line with commands like `archivebox add`, through the built-in Web UI `archivebox server`, or via the Python library API (beta). It can ingest bookmarks from a browser or service like Pocket/Pinboard, your entire browsing history, RSS feeds, or URLs one at a time. You can also schedule regular/realtime imports with `archivebox schedule`.
 
diff --git a/archivebox/core/migrations/0008_auto_20210105_1421.py b/archivebox/core/migrations/0008_auto_20210105_1421.py
new file mode 100644
index 00000000..e5b3387d
--- /dev/null
+++ b/archivebox/core/migrations/0008_auto_20210105_1421.py
@@ -0,0 +1,18 @@
+# Generated by Django 3.1.3 on 2021-01-05 14:21
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('core', '0007_archiveresult'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='archiveresult',
+            name='cmd_version',
+            field=models.CharField(blank=True, default=None, max_length=32, null=True),
+        ),
+    ]
diff --git a/archivebox/core/models.py b/archivebox/core/models.py
index d50e8f40..13d75b66 100644
--- a/archivebox/core/models.py
+++ b/archivebox/core/models.py
@@ -181,7 +181,7 @@ class ArchiveResult(models.Model):
     snapshot = models.ForeignKey(Snapshot, on_delete=models.CASCADE)
     cmd = JSONField()
     pwd = models.CharField(max_length=256)
-    cmd_version = models.CharField(max_length=32)
+    cmd_version = models.CharField(max_length=32, default=None, null=True, blank=True)
     output = models.CharField(max_length=512)
     start_ts = models.DateTimeField()
     end_ts = models.DateTimeField()
diff --git a/archivebox/index/__init__.py b/archivebox/index/__init__.py
index 4f4ac3d4..8eab1d38 100644
--- a/archivebox/index/__init__.py
+++ b/archivebox/index/__init__.py
@@ -124,7 +124,7 @@ def validate_links(links: Iterable[Link]) -> List[Link]:
     timer = TimedProgress(TIMEOUT * 4)
     try:
         links = archivable_links(links)  # remove chrome://, about:, mailto: etc.
-        links = sorted_links(links)      # deterministically sort the links based on timstamp, url
+        links = sorted_links(links)      # deterministically sort the links based on timestamp, url
         links = fix_duplicate_links(links)  # merge/dedupe duplicate timestamps & urls
     finally:
         timer.end()