diff --git a/core/imageboard/tag.php b/core/imageboard/tag.php
index 95c266ccb..939db1d8b 100644
--- a/core/imageboard/tag.php
+++ b/core/imageboard/tag.php
@@ -129,7 +129,7 @@ public static function implode(array $tags): string
     /**
      * Turn a human-supplied string into a valid tag array.
      *
-     * @return string[]
+     * @return list<string>
      */
     public static function explode(string $tags, bool $tagme = true): array
     {
diff --git a/ext/index/events.php b/ext/index/events.php
index d3ebb3ddc..8f640fa05 100644
--- a/ext/index/events.php
+++ b/ext/index/events.php
@@ -35,7 +35,7 @@ public function __construct(int $id, ?string $term = null, array $context = [])
 
         if ($term !== null) {
             // pull any operands off the start of the search term
-            while (is_string($term) && !empty($term) && array_key_exists($term[0], TAG_OPERANDS)) {
+            while (!empty($term) && array_key_exists($term[0], TAG_OPERANDS)) {
                 $operand = TAG_OPERANDS[$term[0]];
                 $term = substr($term, 1);
                 $this->$operand = true;
diff --git a/ext/ouroboros_api/main.php b/ext/ouroboros_api/main.php
index 1ea16e02c..381f841f3 100644
--- a/ext/ouroboros_api/main.php
+++ b/ext/ouroboros_api/main.php
@@ -419,9 +419,6 @@ protected function postIndex(int $limit, int $page, array $tags): void
         $results = Search::find_images(max($start, 0), min($limit, 100), $tags);
         $posts = [];
         foreach ($results as $img) {
-            if (!is_object($img)) {
-                continue;
-            }
             $posts[] = new _SafeOuroborosImage($img);
         }
         $this->sendData('post', $posts, max($start, 0));
diff --git a/ext/post_tags/main.php b/ext/post_tags/main.php
index b033f5b77..67ec884ac 100644
--- a/ext/post_tags/main.php
+++ b/ext/post_tags/main.php
@@ -109,7 +109,7 @@ public function matches(string $regex): ?array
     {
         $matches = [];
         if (\Safe\preg_match($regex, $this->term, $matches) === 1) {
-            return $matches;
+            return array_values($matches);
         }
         return null;
     }
diff --git a/ext/random_image/test.php b/ext/random_image/test.php
index 6d45b79ce..e01ac1a1a 100644
--- a/ext/random_image/test.php
+++ b/ext/random_image/test.php
@@ -19,7 +19,7 @@ public function testRandom(): void
         $this->assertEquals("Post $image_id: test", $page->title);
 
         $page = $this->get_page("random_image/download");
-        $this->assertNotNull($page->data);
+        $this->assertEquals($page->mode, PageMode::FILE);
         # FIXME: assert($raw == file(blah.jpg))
     }
 
@@ -37,7 +37,7 @@ public function testPostListBlock(): void
         # enabled, image = text
         $image_id = $this->post_image("tests/pbx_screenshot.jpg", "test");
         $page = $this->get_page("post/list");
-        $this->assertNotNull($page->find_block("Random Post"));
+        $page->find_block("Random Post"); // will throw if missing
 
         # disabled, image = no text
         $config->set_bool("show_random_block", false);
diff --git a/ext/user/events.php b/ext/user/events.php
index 82042efe9..06233cefd 100644
--- a/ext/user/events.php
+++ b/ext/user/events.php
@@ -44,7 +44,7 @@ public function __construct(
 
 class UserCreationEvent extends Event
 {
-    private ?User $user;
+    private ?User $user = null;
 
     public function __construct(
         public string $username,
diff --git a/ext/word_filter/main.php b/ext/word_filter/main.php
index c2f070b6c..b73a35d58 100644
--- a/ext/word_filter/main.php
+++ b/ext/word_filter/main.php
@@ -37,7 +37,6 @@ private function filter(string $text): string
                 $search = "/\\b" . str_replace("/", "\\/", $search) . "\\b/i";
                 $text = preg_replace_ex($search, $replace, $text);
             }
-            assert(is_string($text));
         }
         return $text;
     }