diff --git a/themes/danbooru/themelet.class.php b/themes/danbooru/themelet.class.php
index a00a75d4..9cdf2507 100644
--- a/themes/danbooru/themelet.class.php
+++ b/themes/danbooru/themelet.class.php
@@ -10,13 +10,13 @@ class Themelet extends BaseThemelet
         $page->add_block(new Block(null, $body, "main", 90));
     }
 
-    private function gen_page_link(string $base_url, string $query, string $page, string $name): string
+    private function gen_page_link(string $base_url, ?string $query, string $page, string $name): string
     {
         $link = make_link("$base_url/$page", $query);
         return "<a href='$link'>$name</a>";
     }
 
-    private function gen_page_link_block(string $base_url, string $query, int $page, int $current_page, string $name): string
+    private function gen_page_link_block(string $base_url, ?string $query, int $page, int $current_page, string $name): string
     {
         $paginator = "";
         if ($page == $current_page) {
@@ -27,7 +27,7 @@ class Themelet extends BaseThemelet
         return $paginator;
     }
 
-    private function build_paginator(int $current_page, int $total_pages, string $base_url, string $query): string
+    private function build_paginator(int $current_page, int $total_pages, string $base_url, ?string $query): string
     {
         $next = $current_page + 1;
         $prev = $current_page - 1;
diff --git a/themes/danbooru2/themelet.class.php b/themes/danbooru2/themelet.class.php
index a00a75d4..9cdf2507 100644
--- a/themes/danbooru2/themelet.class.php
+++ b/themes/danbooru2/themelet.class.php
@@ -10,13 +10,13 @@ class Themelet extends BaseThemelet
         $page->add_block(new Block(null, $body, "main", 90));
     }
 
-    private function gen_page_link(string $base_url, string $query, string $page, string $name): string
+    private function gen_page_link(string $base_url, ?string $query, string $page, string $name): string
     {
         $link = make_link("$base_url/$page", $query);
         return "<a href='$link'>$name</a>";
     }
 
-    private function gen_page_link_block(string $base_url, string $query, int $page, int $current_page, string $name): string
+    private function gen_page_link_block(string $base_url, ?string $query, int $page, int $current_page, string $name): string
     {
         $paginator = "";
         if ($page == $current_page) {
@@ -27,7 +27,7 @@ class Themelet extends BaseThemelet
         return $paginator;
     }
 
-    private function build_paginator(int $current_page, int $total_pages, string $base_url, string $query): string
+    private function build_paginator(int $current_page, int $total_pages, string $base_url, ?string $query): string
     {
         $next = $current_page + 1;
         $prev = $current_page - 1;
diff --git a/themes/futaba/themelet.class.php b/themes/futaba/themelet.class.php
index b84d3aae..219dbefb 100644
--- a/themes/futaba/themelet.class.php
+++ b/themes/futaba/themelet.class.php
@@ -17,13 +17,13 @@ class Themelet extends BaseThemelet
     /**
      * Generate a single HTML link.
      */
-    public function futaba_gen_page_link(string $base_url, string $query, string $page, string $name): string
+    public function futaba_gen_page_link(string $base_url, ?string $query, string $page, string $name): string
     {
         $link = make_link("$base_url/$page", $query);
         return "[<a href='$link'>{$name}</a>]";
     }
 
-    public function futaba_gen_page_link_block(string $base_url, string $query, int $page, int $current_page, string $name): string
+    public function futaba_gen_page_link_block(string $base_url, ?string $query, int $page, int $current_page, string $name): string
     {
         $paginator = "";
         if ($page == $current_page) {
@@ -36,7 +36,7 @@ class Themelet extends BaseThemelet
         return $paginator;
     }
 
-    public function futaba_build_paginator(int $current_page, int $total_pages, string $base_url, string $query): string
+    public function futaba_build_paginator(int $current_page, int $total_pages, string $base_url, ?string $query): string
     {
         $next = $current_page + 1;
         $prev = $current_page - 1;
diff --git a/themes/lite/themelet.class.php b/themes/lite/themelet.class.php
index ef64903d..4e4ad20f 100644
--- a/themes/lite/themelet.class.php
+++ b/themes/lite/themelet.class.php
@@ -33,7 +33,7 @@ class Themelet extends BaseThemelet
         return "<a class='$link_class' href='$link'>$name</a>";
     }
 
-    public function litetheme_gen_page_link_block(string $base_url, string $query, string $page, string $current_page, string $name): string
+    public function litetheme_gen_page_link_block(string $base_url, ?string $query, string $page, string $current_page, string $name): string
     {
         $paginator = "";
 
@@ -47,7 +47,7 @@ class Themelet extends BaseThemelet
         return $paginator;
     }
 
-    public function litetheme_build_paginator(int $current_page, int $total_pages, string $base_url, string $query, bool $show_random): string
+    public function litetheme_build_paginator(int $current_page, int $total_pages, string $base_url, ?string $query, bool $show_random): string
     {
         $next = $current_page + 1;
         $prev = $current_page - 1;