diff --git a/content_scripts/create_total_cards_button.js b/content_scripts/create_total_cards_button.js
index dbaeda5..5cb8224 100644
--- a/content_scripts/create_total_cards_button.js
+++ b/content_scripts/create_total_cards_button.js
@@ -6,19 +6,16 @@
     // Count number of cards.
     const numberOfCards = document.querySelectorAll(".list-card").length;
 
-    // Create on/off button instance.
-    const buttonInstance = document.getElementById("button-total-cards-count");
-
-    // Create HTML for button.
-    const numberOfCardsButtonHTML = `<a id="button-total-cards-count" class="board-header-btn board-header-btn-invite ' +
-    'board-header-btn-without-icon" title="Invite to board"><span class="board-header-btn-text">' +
-    'Total cards: <b>' ${numberOfCards} '</b></span></a>`;
-
-    // Inner HTML of header buttons
-    let boardHeaderButtons = document.getElementsByClassName(
-        "board-header-btns mod-left"
-    )[1].innerHTML;
-
     // Check if button already exists before creating it.
-    if (!buttonInstance) boardHeaderButtons += numberOfCardsButtonHTML;
-})();
+    let buttonInstance = document.getElementById("button-total-cards-count");
+    if (buttonInstance === null) {
+        // Create HTML for button.
+        let numberOfCardsButtonHTML = '<a id="button-total-cards-count" class="board-header-btn board-header-btn-invite ' +
+            'board-header-btn-without-icon" title="Invite to board"><span class="board-header-btn-text">' +
+            'Total cards: <b>' + numberOfCards + '</b></span></a>'
+        // Add button to Trello board.
+        document.getElementsByClassName("board-header-btns mod-left")[1].innerHTML += numberOfCardsButtonHTML;
+    } else {
+        // Do nothing.
+    }
+})();
\ No newline at end of file