diff --git a/markups/markdown.py b/markups/markdown.py
index c948ef7..20ebcc5 100644
--- a/markups/markdown.py
+++ b/markups/markdown.py
@@ -215,7 +215,7 @@ def _apply_extensions(
                 extension_names.add(canonical_name)
                 extension_configs[canonical_name] = config
         self.md = self.markdown.Markdown(
-            extensions=list(extension_names),
+            extensions=sorted(extension_names),
             extension_configs=extension_configs,
             output_format="html5",
         )