diff --git a/js/build_page.js b/js/build_page.js
index 81b76ed..13a8a3a 100644
--- a/js/build_page.js
+++ b/js/build_page.js
@@ -113,7 +113,7 @@
     var duplicateSubjectBoolNext, duplicateSubjectBoolPrev;
     var duplicateSubjectCounter = 0;
     
-    for (var [i, classe] of classes) {        
+    for (var [i, classe] of classes.entries()) {        
         var hora_inici = formatDate(new Date(parseInt(classe.begins)*1000));
         var hora_final = formatDate(new Date(parseInt(classe.ends)*1000));
         var classeDiv = document.createElement('div');