diff --git a/public/index.php b/public/index.php
index e75f3de..6ab514e 100644
--- a/public/index.php
+++ b/public/index.php
@@ -42,10 +42,10 @@ $chosen_date_time = new DateTime($chosen_date);
 <body>
 <form id="date_form" style="align-self: center; width: 500px; display: grid; grid-template-columns: 20% 20% 20% 20% 20%; gap: 10px;" action="/index.php" method="post">
     <?php
-    $chosen_date_time->modify('-1 month');
     if ($dates['first'] < $chosen_date_time) {
-        echo "<button type='button' onclick='submit_form(\"" . $chosen_date_time->format('Y-m') . "\")'><</button>";
+        echo "<button type='button' onclick='submit_form(\"" . $chosen_date_time->modify('-1 month')->format('Y-m') . "\")'><</button>";
     } else {
+        $chosen_date_time->modify('-1 month');
         echo '<span></span>';
     }
     $chosen_date_time->modify('+1 month');
