diff --git a/markdownify/main.py b/markdownify/main.py
index ba70671..c0c96cd 100755
--- a/markdownify/main.py
+++ b/markdownify/main.py
@@ -26,7 +26,7 @@ def main(argv=sys.argv[1:]):
     parser.add_argument('-a', '--autolinks', action='store_true',
                         help="A boolean indicating whether the 'automatic link' style "
                         "should be used when a 'a' tag's contents match its href.")
-    parser.add_argument('--default-title', action='store_false',
+    parser.add_argument('--default-title', action='store_true',
                         help="A boolean to enable setting the title of a link to its "
                         "href, if no title is given.")
     parser.add_argument('--heading-style', default=UNDERLINED,
diff --git a/tests/test_main.py b/tests/test_main.py
new file mode 100644
index 0000000..a8b72aa
--- /dev/null
+++ b/tests/test_main.py
@@ -0,0 +1,42 @@
+from io import StringIO
+import sys
+
+from markdownify.main import main
+
+
+def test_cli_stdin_default_and_flag(monkeypatch, capfd):
+    html = '<a href="https://example.com">Example</a>'
+
+    monkeypatch.setattr(sys, 'stdin', StringIO(html))
+    main([])
+    assert capfd.readouterr().out == '[Example](https://example.com)\n'
+
+    monkeypatch.setattr(sys, 'stdin', StringIO(html))
+    main(['--default-title'])
+    assert capfd.readouterr().out == '[Example](https://example.com "https://example.com")\n'
+
+
+def test_cli_named_file_and_explicit_title(tmp_path, monkeypatch, capfd):
+    source = tmp_path / 'input.html'
+    source.write_text(
+        '<a href="https://example.com" title="Custom">Example</a>',
+        encoding='utf-8',
+    )
+
+    main([str(source)])
+    assert capfd.readouterr().out == '[Example](https://example.com "Custom")\n'
+
+    main(['--default-title', str(source)])
+    assert capfd.readouterr().out == '[Example](https://example.com "Custom")\n'
+
+
+def test_cli_autolinks_option_is_unchanged(monkeypatch, capfd):
+    html = '<a href="https://example.com">https://example.com</a>'
+
+    monkeypatch.setattr(sys, 'stdin', StringIO(html))
+    main(['-a'])
+    assert capfd.readouterr().out == '<https://example.com>\n'
+
+    monkeypatch.setattr(sys, 'stdin', StringIO(html))
+    main(['-a', '--default-title'])
+    assert capfd.readouterr().out == '[https://example.com](https://example.com "https://example.com")\n'