diff --git a/core/polyfills.php b/core/polyfills.php
index 365e9ddb..b4177c02 100644
--- a/core/polyfills.php
+++ b/core/polyfills.php
@@ -3,35 +3,6 @@
 * Things which should be in the core API                                    *
 \* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
 
-/**
- * Remove an item from an array
- */
-function array_remove(array $array, $to_remove): array
-{
-    $array = array_unique($array);
-    $a2 = [];
-    foreach ($array as $existing) {
-        if ($existing != $to_remove) {
-            $a2[] = $existing;
-        }
-    }
-    return $a2;
-}
-
-/**
- * Adds an item to an array.
- *
- * Also removes duplicate values from the array.
- */
-function array_add(array $array, $element): array
-{
-    // Could we just use array_push() ?
-    //  http://www.php.net/manual/en/function.array-push.php
-    $array[] = $element;
-    $array = array_unique($array);
-    return $array;
-}
-
 /**
  * Return the unique elements of an array, case insensitively
  */
diff --git a/ext/tag_list/theme.php b/ext/tag_list/theme.php
index b0af98bd..6f771871 100644
--- a/ext/tag_list/theme.php
+++ b/ext/tag_list/theme.php
@@ -227,7 +227,7 @@ class TagListTheme extends Themelet
         $display_html = '';
         $tag = $row['tag'];
         $h_tag = html_escape($tag);
-        
+
         $tag_category_css = '';
         $tag_category_style = '';
         $h_tag_split = explode(':', html_escape($tag), 2);
@@ -277,8 +277,7 @@ class TagListTheme extends Themelet
         if (!in_array($tag, $tags) && !in_array("-$tag", $tags)) {
             return "";
         } else {
-            $tags = array_remove($tags, $tag);
-            $tags = array_remove($tags, "-$tag");
+            $tags = array_diff($tags, [$tag, "-$tag"]);
             return "<a href='".$this->tag_link(join(' ', $tags))."' title='Remove' rel='nofollow'>R</a>";
         }
     }
@@ -288,8 +287,7 @@ class TagListTheme extends Themelet
         if (in_array($tag, $tags)) {
             return "";
         } else {
-            $tags = array_remove($tags, "-$tag");
-            $tags = array_add($tags, $tag);
+            $tags = array_diff($tags, ["-$tag"]) + [$tag];
             return "<a href='".$this->tag_link(join(' ', $tags))."' title='Add' rel='nofollow'>A</a>";
         }
     }
@@ -299,8 +297,7 @@ class TagListTheme extends Themelet
         if (in_array("-$tag", $tags)) {
             return "";
         } else {
-            $tags = array_remove($tags, $tag);
-            $tags = array_add($tags, "-$tag");
+            $tags = array_diff($tags, [$tag]) + ["-$tag"];
             return "<a href='".$this->tag_link(join(' ', $tags))."' title='Subtract' rel='nofollow'>S</a>";
         }
     }