diff --git a/packages/mermaid/src/diagrams/class/classDb.ts b/packages/mermaid/src/diagrams/class/classDb.ts
index 7a45c9008..6bcb29b1d 100644
--- a/packages/mermaid/src/diagrams/class/classDb.ts
+++ b/packages/mermaid/src/diagrams/class/classDb.ts
@@ -476,11 +476,11 @@ export class ClassDB implements DiagramDB {
   // Utility function to escape HTML meta-characters
   private escapeHtml(str: string): string {
     return str
-      .replace(/&/g, "&")
-      .replace(/</g, "&lt;")
-      .replace(/>/g, "&gt;")
-      .replace(/"/g, "&quot;")
-      .replace(/'/g, "&#39;");
+      .replace(/&/g, '&amp;')
+      .replace(/</g, '&lt;')
+      .replace(/>/g, '&gt;')
+      .replace(/"/g, '&quot;')
+      .replace(/'/g, '&#39;');
   }
 
   private readonly setupToolTips = (element: Element) => {