diff --git a/packages/mermaid/src/schemas/config.schema.yaml b/packages/mermaid/src/schemas/config.schema.yaml
index 6c5fde21c..55c063662 100644
--- a/packages/mermaid/src/schemas/config.schema.yaml
+++ b/packages/mermaid/src/schemas/config.schema.yaml
@@ -65,6 +65,8 @@ properties:
       - dark
       - forest
       - neutral
+      - neo
+      - neo-dark
       - 'null' # should this be a `null`-type?
     meta:enum:
       'null': Can be set to disable any pre-defined mermaid theme