diff --git a/packages/mermaid/src/diagrams/treemap/db.ts b/packages/mermaid/src/diagrams/treemap/db.ts
index 23326bc85..93793eb1d 100644
--- a/packages/mermaid/src/diagrams/treemap/db.ts
+++ b/packages/mermaid/src/diagrams/treemap/db.ts
@@ -21,6 +21,10 @@ export class TreeMapDB implements DiagramDB {
   private classes: Map<string, DiagramStyleClassDef> = new Map<string, DiagramStyleClassDef>();
   private root?: TreemapNode;
 
+  constructor() {
+    this.clear();
+  }
+
   public getNodes() {
     return this.nodes;
   }