diff --git a/packages/mermaid/src/config.type.ts b/packages/mermaid/src/config.type.ts
index 454655105..600a9edfe 100644
--- a/packages/mermaid/src/config.type.ts
+++ b/packages/mermaid/src/config.type.ts
@@ -61,7 +61,7 @@ export interface MermaidConfig {
    * You may also use `themeCSS` to override this value.
    *
    */
-  theme?: 'default' | 'base' | 'dark' | 'forest' | 'neutral' | 'neo' | 'neo-dark' | 'null';
+  theme?: 'default' | 'base' | 'dark' | 'forest' | 'neutral' | 'neo' | 'neo-dark' | 'mc' | 'null';
   themeVariables?: any;
   themeCSS?: string;
   /**
diff --git a/packages/mermaid/src/schemas/config.schema.yaml b/packages/mermaid/src/schemas/config.schema.yaml
index 55c063662..7223aba25 100644
--- a/packages/mermaid/src/schemas/config.schema.yaml
+++ b/packages/mermaid/src/schemas/config.schema.yaml
@@ -67,6 +67,7 @@ properties:
       - neutral
       - neo
       - neo-dark
+      - mc
       - 'null' # should this be a `null`-type?
     meta:enum:
       'null': Can be set to disable any pre-defined mermaid theme