diff --git a/core/_install.php b/core/_install.php
index 1b78499e..bf99bc21 100644
--- a/core/_install.php
+++ b/core/_install.php
@@ -364,19 +364,10 @@ function insert_defaults()
 
 function build_dirs()
 { // {{{
-    // *try* and make default dirs. Ignore any errors --
-    // if something is amiss, we'll tell the user later
-    if (!file_exists("data")) {
-        @mkdir("data");
-    }
-    if (!is_writable("data")) {
-        @chmod("data", 0755);
-    }
+    $data_exists = file_exists("data") || mkdir("data");
+    $data_writable = is_writable("data") || chmod("data", 0755);
 
-    // Clear file status cache before checking again.
-    clearstatcache();
-
-    if (!file_exists("data") || !is_writable("data")) {
+    if (!$data_exists || !$data_writable) {
         print "
 		<div id='installer'>
 			<h1>Shimmie Installer</h1>
diff --git a/core/database.php b/core/database.php
index 124d7c31..24d8bd47 100644
--- a/core/database.php
+++ b/core/database.php
@@ -203,7 +203,8 @@ class Database
             $stmt = $this->db->prepare(
                 "-- " . str_replace("%2F", "/", urlencode(@$_GET['q'])). "\n" .
                 $query
-            );
+            )
+			assert(!is_bool($stmt));;
             // $stmt = $this->db->prepare($query);
             if (!array_key_exists(0, $args)) {
                 foreach ($args as $name=>$value) {
@@ -308,10 +309,12 @@ class Database
     public function get_last_insert_id(string $seq): int
     {
         if ($this->engine->name == DatabaseDriver::PGSQL) {
-            return $this->db->lastInsertId($seq);
+            $id = $this->db->lastInsertId($seq);
         } else {
-            return $this->db->lastInsertId();
+            $id = $this->db->lastInsertId();
         }
+		assert(is_numeric($id));
+		return (int)$id;
     }
 
     /**
diff --git a/core/extension.php b/core/extension.php
index d09170cf..30468135 100644
--- a/core/extension.php
+++ b/core/extension.php
@@ -225,12 +225,12 @@ abstract class ExtensionInfo
 
     protected function __construct()
     {
-        assert (!empty($this->key), "key field is required");
-        assert (!empty($this->name), "name field is required for extension $this->key");
-        assert (empty($this->visibility) || in_array($this->visibility, self::VALID_VISIBILITY), "Invalid visibility for extension $this->key");
-        assert (is_array($this->db_support), "db_support has to be an array for extension $this->key");
-        assert (is_array($this->authors), "authors has to be an array for extension $this->key");
-        assert (is_array($this->dependencies), "dependencies has to be an array for extension $this->key");
+        assert(!empty($this->key), "key field is required");
+        assert(!empty($this->name), "name field is required for extension $this->key");
+        assert(empty($this->visibility) || in_array($this->visibility, self::VALID_VISIBILITY), "Invalid visibility for extension $this->key");
+        assert(is_array($this->db_support), "db_support has to be an array for extension $this->key");
+        assert(is_array($this->authors), "authors has to be an array for extension $this->key");
+        assert(is_array($this->dependencies), "dependencies has to be an array for extension $this->key");
     }
 
     public function is_enabled(): bool