diff --git a/js/worker.js b/js/worker.js
index 29ef632..e91424e 100644
--- a/js/worker.js
+++ b/js/worker.js
@@ -29,7 +29,7 @@ function doConvert(input, config){
 
         let sheetsData;
         if (config.sheet) {
-            const data = xlsx.get_sheet_data(sheet);
+            const data = xlsx.get_sheet_data(config.sheet);
             sheetsData = [data];
         } else {
             const sheets = xlsx.get_sheets();
@@ -49,4 +49,4 @@ function doConvert(input, config){
             doConvert(input, config);
         }).catch(e => console.log(e));
     }
-}
\ No newline at end of file
+}