diff --git a/public/scripts/tool-calling.js b/public/scripts/tool-calling.js
index 0eaada477..e0e3c53e0 100644
--- a/public/scripts/tool-calling.js
+++ b/public/scripts/tool-calling.js
@@ -278,9 +278,9 @@ export class ToolManager {
             }
 
             for (const toolCallDelta of toolCallDeltas) {
-                const toolCallIndex = (typeof toolCallDelta?.index === 'number') ? toolCallDelta.index : null;
+                const toolCallIndex = (typeof toolCallDelta?.index === 'number') ? toolCallDelta.index : toolCallDeltas.indexOf(toolCallDelta);
 
-                if (toolCallIndex === null) {
+                if (isNaN(toolCallIndex) || toolCallIndex < 0) {
                     continue;
                 }