diff --git a/webview-ui/src/components/common/MermaidBlock.tsx b/webview-ui/src/components/common/MermaidBlock.tsx
index c5fc8b30bb..7d483d9c4f 100644
--- a/webview-ui/src/components/common/MermaidBlock.tsx
+++ b/webview-ui/src/components/common/MermaidBlock.tsx
@@ -243,7 +243,8 @@ async function svgToPng(svgEl: SVGElement): Promise<string> {
 
 	const serializer = new XMLSerializer()
 	const svgString = serializer.serializeToString(svgClone)
-	const svgDataUrl = "data:image/svg+xml;base64," + btoa(decodeURIComponent(encodeURIComponent(svgString)))
+
+	const svgDataUrl = `data:image/svg+xml;charset=utf-8,${encodeURIComponent(svgString)}`
 
 	return new Promise((resolve, reject) => {
 		const img = new Image()