diff --git a/sphinxcontrib/mermaid/autoclassdiag.py b/sphinxcontrib/mermaid/autoclassdiag.py
index 5f4f99d..35cc7f6 100644
--- a/sphinxcontrib/mermaid/autoclassdiag.py
+++ b/sphinxcontrib/mermaid/autoclassdiag.py
@@ -1,6 +1,7 @@
 import inspect
 
-from sphinx.util import ExtensionError, import_object
+from sphinx.errors import ExtensionError
+from sphinx.util import import_object
 
 from .exceptions import MermaidError