From 7e8631dd196e9bca7d1fdbc9346d9037e783102d Mon Sep 17 00:00:00 2001
From: Michael Maier <maier1michael@gmail.com>
Date: Mon, 10 Oct 2022 17:59:29 +0200
Subject: [PATCH] fix: vertex property `props` is overwritten instead of being
 merged with new value

Fixes #3263
---
 packages/mermaid/src/diagrams/flowchart/flowDb.js | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/packages/mermaid/src/diagrams/flowchart/flowDb.js b/packages/mermaid/src/diagrams/flowchart/flowDb.js
index 5aa203225..34efa86d8 100644
--- a/packages/mermaid/src/diagrams/flowchart/flowDb.js
+++ b/packages/mermaid/src/diagrams/flowchart/flowDb.js
@@ -119,7 +119,11 @@ export const addVertex = function (_id, text, type, style, classes, dir, props =
   if (typeof dir !== 'undefined') {
     vertices[id].dir = dir;
   }
-  vertices[id].props = props;
+  if (typeof vertices[id].props === 'undefined') {
+    vertices[id].props = props;
+  } else if (typeof props !== 'undefined') {
+    Object.assign(vertices[id].props, props);
+  }
 };
 
 /**