diff --git a/docs/reference/diagrams.md b/docs/reference/diagrams.md
index 713037e50..52951f0c3 100644
--- a/docs/reference/diagrams.md
+++ b/docs/reference/diagrams.md
@@ -29,7 +29,7 @@ markdown_extensions:
       custom_fences:
         - name: mermaid
           class: mermaid-experimental
-          format: !!pymdownx.superfences.fence_code_format
+          format: !!python/name:pymdownx.superfences.fence_code_format
 ```
 
 No further configuration is necessary. Material for MkDocs will automatically