diff --git a/phpstan-baseline.php b/phpstan-baseline.php
index d3a50f311dcb..9665737db821 100644
--- a/phpstan-baseline.php
+++ b/phpstan-baseline.php
@@ -16,11 +16,6 @@
 	'count' => 1,
 	'path' => __DIR__ . '/system/BaseModel.php',
 ];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\Cache\\\\CacheInterface\\:\\:initialize\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/Cache/CacheInterface.php',
-];
 $ignoreErrors[] = [
 	'message' => '#^Method CodeIgniter\\\\Cache\\\\Handlers\\\\BaseHandler\\:\\:deleteMatching\\(\\) has no return type specified\\.$#',
 	'count' => 1,
@@ -36,11 +31,6 @@
 	'count' => 1,
 	'path' => __DIR__ . '/system/Cache/Handlers/DummyHandler.php',
 ];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\Cache\\\\Handlers\\\\DummyHandler\\:\\:initialize\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/Cache/Handlers/DummyHandler.php',
-];
 $ignoreErrors[] = [
 	'message' => '#^Method CodeIgniter\\\\Cache\\\\Handlers\\\\DummyHandler\\:\\:remember\\(\\) has parameter \\$callback with no signature specified for Closure\\.$#',
 	'count' => 1,
@@ -51,51 +41,26 @@
 	'count' => 1,
 	'path' => __DIR__ . '/system/Cache/Handlers/FileHandler.php',
 ];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\Cache\\\\Handlers\\\\FileHandler\\:\\:initialize\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/Cache/Handlers/FileHandler.php',
-];
 $ignoreErrors[] = [
 	'message' => '#^Method CodeIgniter\\\\Cache\\\\Handlers\\\\MemcachedHandler\\:\\:deleteMatching\\(\\) has no return type specified\\.$#',
 	'count' => 1,
 	'path' => __DIR__ . '/system/Cache/Handlers/MemcachedHandler.php',
 ];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\Cache\\\\Handlers\\\\MemcachedHandler\\:\\:initialize\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/Cache/Handlers/MemcachedHandler.php',
-];
 $ignoreErrors[] = [
 	'message' => '#^Method CodeIgniter\\\\Cache\\\\Handlers\\\\PredisHandler\\:\\:deleteMatching\\(\\) has no return type specified\\.$#',
 	'count' => 1,
 	'path' => __DIR__ . '/system/Cache/Handlers/PredisHandler.php',
 ];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\Cache\\\\Handlers\\\\PredisHandler\\:\\:initialize\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/Cache/Handlers/PredisHandler.php',
-];
 $ignoreErrors[] = [
 	'message' => '#^Method CodeIgniter\\\\Cache\\\\Handlers\\\\RedisHandler\\:\\:deleteMatching\\(\\) has no return type specified\\.$#',
 	'count' => 1,
 	'path' => __DIR__ . '/system/Cache/Handlers/RedisHandler.php',
 ];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\Cache\\\\Handlers\\\\RedisHandler\\:\\:initialize\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/Cache/Handlers/RedisHandler.php',
-];
 $ignoreErrors[] = [
 	'message' => '#^Method CodeIgniter\\\\Cache\\\\Handlers\\\\WincacheHandler\\:\\:deleteMatching\\(\\) has no return type specified\\.$#',
 	'count' => 1,
 	'path' => __DIR__ . '/system/Cache/Handlers/WincacheHandler.php',
 ];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\Cache\\\\Handlers\\\\WincacheHandler\\:\\:initialize\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/Cache/Handlers/WincacheHandler.php',
-];
 $ignoreErrors[] = [
 	'message' => '#^Call to an undefined method CodeIgniter\\\\HTTP\\\\Request\\:\\:getPost\\(\\)\\.$#',
 	'count' => 1,
@@ -2286,11 +2251,6 @@
 	'count' => 1,
 	'path' => __DIR__ . '/system/Test/Mock/MockCache.php',
 ];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\Test\\\\Mock\\\\MockCache\\:\\:initialize\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/Test/Mock/MockCache.php',
-];
 $ignoreErrors[] = [
 	'message' => '#^Method CodeIgniter\\\\Test\\\\Mock\\\\MockCache\\:\\:remember\\(\\) has parameter \\$callback with no signature specified for Closure\\.$#',
 	'count' => 1,
diff --git a/system/Cache/CacheInterface.php b/system/Cache/CacheInterface.php
index d50322e778f6..23ea709df482 100644
--- a/system/Cache/CacheInterface.php
+++ b/system/Cache/CacheInterface.php
@@ -18,6 +18,8 @@ interface CacheInterface
 {
     /**
      * Takes care of any handler-specific setup that must be done.
+     *
+     * @return void
      */
     public function initialize();
 
diff --git a/system/Test/Mock/MockCache.php b/system/Test/Mock/MockCache.php
index f0414bb8bf02..73a755802285 100644
--- a/system/Test/Mock/MockCache.php
+++ b/system/Test/Mock/MockCache.php
@@ -42,6 +42,8 @@ class MockCache extends BaseHandler implements CacheInterface
 
     /**
      * Takes care of any handler-specific setup that must be done.
+     *
+     * @return void
      */
     public function initialize()
     {