diff --git a/docs/architecture/diagrams/model_timeline.md b/docs/architecture/diagrams/model_timeline.md
index 4a39807a1..8591e660b 100644
--- a/docs/architecture/diagrams/model_timeline.md
+++ b/docs/architecture/diagrams/model_timeline.md
@@ -19,7 +19,7 @@ A more complete diagram of the data models, their fields, and their
 relationships are in [models_diagram.md](./models_diagram.md), created with
 the `django-model2puml` plugin.
 
-```plantuml
+```mermaid
 @startuml
 
 allowmixing
diff --git a/docs/architecture/diagrams/models_diagram.md b/docs/architecture/diagrams/models_diagram.md
index 5e47514d0..b06c8807a 100644
--- a/docs/architecture/diagrams/models_diagram.md
+++ b/docs/architecture/diagrams/models_diagram.md
@@ -8,7 +8,7 @@ using the command
 $ docker compose app ./manage.py generate_puml --include registrar
 ```
 
-```plantuml
+```mermaid
 @startuml 
 class "registrar.Contact <Registrar>" as registrar.Contact #d6f4e9 {
     contact