diff --git a/packages/mermaid/src/diagrams/flowchart/flowDb.ts b/packages/mermaid/src/diagrams/flowchart/flowDb.ts
index 23a066523..a2956b5d8 100644
--- a/packages/mermaid/src/diagrams/flowchart/flowDb.ts
+++ b/packages/mermaid/src/diagrams/flowchart/flowDb.ts
@@ -14,7 +14,15 @@ import {
   setDiagramTitle,
   getDiagramTitle,
 } from '../common/commonDb.js';
-import type { FlowVertex, FlowClass, FlowSubGraph, FlowText, FlowEdge, FlowLink } from './types.js';
+import type {
+  FlowVertex,
+  FlowClass,
+  FlowSubGraph,
+  FlowText,
+  FlowEdge,
+  FlowLink,
+  FlowVertexTypeParam,
+} from './types.js';
 import type { NodeMetaData } from '../../types.js';
 
 const MERMAID_DOM_ID_PREFIX = 'flowchart-';
@@ -53,12 +61,11 @@ export const lookUpDomId = function (id: string) {
 
 /**
  * Function called by parser when a node definition has been found
- *
  */
 export const addVertex = function (
   id: string,
   textObj: FlowText,
-  type: 'group',
+  type: FlowVertexTypeParam,
   style: string[],
   classes: string[],
   dir: string,
diff --git a/packages/mermaid/src/diagrams/flowchart/types.ts b/packages/mermaid/src/diagrams/flowchart/types.ts
index 770ee24b4..2767f09b4 100644
--- a/packages/mermaid/src/diagrams/flowchart/types.ts
+++ b/packages/mermaid/src/diagrams/flowchart/types.ts
@@ -1,3 +1,26 @@
+/**
+ * Valid `type` args to `yy.addVertex` taken from
+ * `packages/mermaid/src/diagrams/flowchart/parser/flow.jison`
+ */
+export type FlowVertexTypeParam =
+  | undefined
+  | 'square'
+  | 'doublecircle'
+  | 'circle'
+  | 'ellipse'
+  | 'stadium'
+  | 'subroutine'
+  | 'rect'
+  | 'cylinder'
+  | 'round'
+  | 'diamond'
+  | 'hexagon'
+  | 'odd'
+  | 'trapezoid'
+  | 'inv_trapezoid'
+  | 'lean_right'
+  | 'lean_left';
+
 export interface FlowVertex {
   classes: string[];
   dir?: string;