diff --git a/js/common/plotter.js b/js/common/plotter.js
index c80a8e8..f0e6303 100644
--- a/js/common/plotter.js
+++ b/js/common/plotter.js
@@ -48,7 +48,7 @@ export function plotValues(chartObj, serialMessage, bufferSize) {
 
         // handle possible tuple in textLine
         if (textLine.startsWith("(") && textLine.endsWith(")")) {
-            textValues = textLine.substring(1, textLine.length - 1).trim();
+            let textValues = textLine.substring(1, textLine.length - 1).trim();
             // Python tuples can end with a comma, but JS arrays cannot
             if (textValues.endsWith(",")) {
                 textValues = textValues.substring(0, textValues.length - 1);