diff --git a/js/build_page.js b/js/build_page.js
index 6a2ee0a..2c80793 100644
--- a/js/build_page.js
+++ b/js/build_page.js
@@ -125,10 +125,18 @@
         var classeDiv;
         
         // Check if the subject is repeated
-        if (i < classes.length - 1) duplicateSubjectBoolNext = classes[i+1].friendly_name == classe.friendly_name;
-        else duplicateSubjectBoolNext = false;
-        if (i > 0) duplicateSubjectBoolPrev = classes[i-1].friendly_name == classe.friendly_name;
-        else duplicateSubjectBoolPrev = false;
+        if (i < classes.length - 1) {
+            duplicateSubjectBoolNext = classes[i+1].friendly_name == classe.friendly_name;
+        }
+        else { 
+            duplicateSubjectBoolNext = false;
+        }
+        if (i > 0) {
+            duplicateSubjectBoolPrev = classes[i-1].friendly_name == classe.friendly_name;
+        }
+        else {
+            duplicateSubjectBoolPrev = false;
+        }
         
         // Change the previous classeDiv
         if(duplicateSubjectBoolNext && duplicateSubjectCounter%2 == 1) {