diff --git a/core/basethemelet.php b/core/basethemelet.php
index 3461eed3..1d3735f6 100644
--- a/core/basethemelet.php
+++ b/core/basethemelet.php
@@ -202,7 +202,7 @@ class BaseThemelet
      * @param bool $empty_option Whether the first option should be an empty one.
      * @param array $selected_options The values of options that should be pre-selected.
      */
-    protected function build_selector(string $name, array $options, bool $required=false, bool $multiple=false, bool $empty_option=false, array $selected_options=[]): string
+    protected function build_selector(string $name, array $options, bool $required=false, bool $multiple=false, bool $empty_option=false, array $selected_options=[]): HTMLElement
     {
         $attrs = [];
         if ($required) {
@@ -228,6 +228,6 @@ class BaseThemelet
             }
         }
 
-        return (string)$s;
+        return $s;
     }
 }
diff --git a/ext/pools/theme.php b/ext/pools/theme.php
index 9dd7962f..f0c0eca1 100644
--- a/ext/pools/theme.php
+++ b/ext/pools/theme.php
@@ -41,8 +41,7 @@ class PoolsTheme extends Themelet
     public function get_adder_html(Image $image, array $pools): string
     {
         $selector = $this->build_selector("pool_id", $pools);
-        return "\n" . make_form(make_link("pool/add_post")) . "
-            $selector
+        return "\n" . make_form(make_link("pool/add_post")) . $selector . "
             <input type='hidden' name='image_id' value='{$image->id}'>
             <input type='submit' value='Add Post to Pool'>
             </form>
@@ -388,7 +387,7 @@ class PoolsTheme extends Themelet
 
     public function get_bulk_pool_selector(array $options): string
     {
-        return $this->build_selector("bulk_pool_select", $options, required: true, empty_option: true);
+        return (string)$this->build_selector("bulk_pool_select", $options, required: true, empty_option: true);
     }
 
     public function get_bulk_pool_input(array $search_terms): string
diff --git a/ext/rating/theme.php b/ext/rating/theme.php
index 895a3633..f33ed906 100644
--- a/ext/rating/theme.php
+++ b/ext/rating/theme.php
@@ -33,8 +33,8 @@ class RatingsTheme extends Themelet
 
         $html = make_form(make_link("admin/update_ratings"))."<table class='form'>";
 
-        $html .= "<tr><th>Change</th><td>".$this->build_selector("rating_old", $current_ratings, required: true)."</td></tr>";
-        $html .= "<tr><th>To</th><td>".$this->build_selector("rating_new", Ratings::get_ratings_dict(), required: true)."</td></tr>";
+        $html .= "<tr><th>Change</th><td>" . $this->build_selector("rating_old", $current_ratings, required: true) . "</td></tr>";
+        $html .= "<tr><th>To</th><td>" . $this->build_selector("rating_new", Ratings::get_ratings_dict(), required: true) . "</td></tr>";
 
         $html .= "<tr><td colspan='2'><input type='submit' value='Update'></td></tr></table>
         </form>\n";
@@ -44,7 +44,7 @@ class RatingsTheme extends Themelet
 
     public function get_selection_rater_html(array $selected_options, bool $multiple = false): string
     {
-        return $this->build_selector("rating", Ratings::get_ratings_dict(), multiple: $multiple, empty_option: false, selected_options: $selected_options);
+        return (string)$this->build_selector("rating", Ratings::get_ratings_dict(), multiple: $multiple, empty_option: false, selected_options: $selected_options);
     }
 
     public function get_help_html(array $ratings): string