diff --git a/packages/mermaid/src/diagrams/class/classRenderer-v2.ts b/packages/mermaid/src/diagrams/class/classRenderer-v2.ts
index 0f02efa0d..e93611609 100644
--- a/packages/mermaid/src/diagrams/class/classRenderer-v2.ts
+++ b/packages/mermaid/src/diagrams/class/classRenderer-v2.ts
@@ -117,7 +117,7 @@ export const addClasses = function (
         style: styles.style,
         id: vertex.id,
         domId: vertex.domId,
-        tooltip: diagObj.db.getTooltip(vertex.id, parent) || '',
+        tooltip: diagObj.db.getTooltip(vertex.id, parent) ?? '',
         haveCallback: vertex.haveCallback,
         link: vertex.link,
         width: vertex.type === 'group' ? 500 : undefined,