diff --git a/auto_tag_plugin/auto_tag_plugin.php b/auto_tag_plugin/auto_tag_plugin.php
index 60ffb21..7ff599f 100644
--- a/auto_tag_plugin/auto_tag_plugin.php
+++ b/auto_tag_plugin/auto_tag_plugin.php
@@ -152,7 +152,6 @@ function fetch_page_content($url)
 
 function calculate_tags(array $keywordsToTags, array $searchContents): array
 {
-    // Context weights
     $contextWeights = [
         'title' => 3,
         'url' => 3,
@@ -166,16 +165,17 @@ function calculate_tags(array $keywordsToTags, array $searchContents): array
     foreach ($keywordsToTags as $keywords => $tags) {
         $keywordList = explode(',', $keywords);
         foreach ($keywordList as $keyword) {
-            $keyword = trim($keyword);
+            $keyword = preg_quote(trim($keyword), '/');
+            $regex = '/\b' . $keyword . '\b/i';
+
             foreach ($searchContents as $context => $content) {
-                if (stripos($content, $keyword) !== false) {
+                if (preg_match($regex, $content)) {
                     $tagList = explode(',', $tags);
                     foreach ($tagList as $tag) {
                         $tag = trim($tag);
                         if (!isset($tagScores[$tag])) {
                             $tagScores[$tag] = 0;
                         }
-                        // Add weight based on context
                         $tagScores[$tag] += $contextWeights[$context];
                     }
                 }