diff --git a/mike/mkdocs_plugin.py b/mike/mkdocs_plugin.py
index 2b80482..2030ad4 100644
--- a/mike/mkdocs_plugin.py
+++ b/mike/mkdocs_plugin.py
@@ -46,7 +46,7 @@ def on_config(self, config):
         if version and config.get('site_url'):
             if self.config['canonical_version'] is not None:
                 version = self.config['canonical_version']
-            config['site_url'] = urljoin(config['site_url'], version)
+            config['site_url'] = urljoin(config['site_url'], version) + '/'
 
     def on_files(self, files, config):
         if not self.config['version_selector']:
diff --git a/test/unit/test_mkdocs_plugin.py b/test/unit/test_mkdocs_plugin.py
index 9528ca4..559331f 100644
--- a/test/unit/test_mkdocs_plugin.py
+++ b/test/unit/test_mkdocs_plugin.py
@@ -34,7 +34,7 @@ def test_site_url(self):
         with mock.patch('os.environ', {docs_version_var: '1.0'}):
             config = {'site_url': 'https://example.com/'}
             self.make_plugin().on_config(config)
-            self.assertEqual(config['site_url'], 'https://example.com/1.0')
+            self.assertEqual(config['site_url'], 'https://example.com/1.0/')
 
     def test_no_site_url(self):
         with mock.patch('os.environ', {docs_version_var: '1.0'}):
@@ -46,7 +46,7 @@ def test_explicit_canonical(self):
         with mock.patch('os.environ', {docs_version_var: '1.0'}):
             config = {'site_url': 'https://example.com/'}
             self.make_plugin(canonical_version='latest').on_config(config)
-            self.assertEqual(config['site_url'], 'https://example.com/latest')
+            self.assertEqual(config['site_url'], 'https://example.com/latest/')
 
         with mock.patch('os.environ', {docs_version_var: '1.0'}):
             config = {'site_url': 'https://example.com/'}