diff --git a/src/Psalm/Internal/Provider/ParserCacheProvider.php b/src/Psalm/Internal/Provider/ParserCacheProvider.php
index 714b483903a..7d352f5a561 100644
--- a/src/Psalm/Internal/Provider/ParserCacheProvider.php
+++ b/src/Psalm/Internal/Provider/ParserCacheProvider.php
@@ -253,8 +253,10 @@ public function cacheFileContents(string $file_path, string $file_contents): voi
 
     public function deleteOldParserCaches(float $time_before): int
     {
-        // bug in tests, cannot use $this->config, https://github.com/vimeo/psalm/pull/8415#issuecomment-1216982800
-        $cache_directory = Config::getInstance()->getCacheDirectory();
+        $cache_directory = $this->config->getCacheDirectory();
+
+        $this->existing_file_content_hashes = null;
+        $this->new_file_content_hashes = [];
 
         if (!$cache_directory) {
             return 0;
diff --git a/tests/Internal/Provider/ParserInstanceCacheProvider.php b/tests/Internal/Provider/ParserInstanceCacheProvider.php
index 9b81bfcef87..df5215669be 100644
--- a/tests/Internal/Provider/ParserInstanceCacheProvider.php
+++ b/tests/Internal/Provider/ParserInstanceCacheProvider.php
@@ -82,6 +82,18 @@ public function cacheFileContents(string $file_path, string $file_contents): voi
         $this->file_contents_cache[$file_path] = $file_contents;
     }
 
+    public function deleteOldParserCaches(): int
+    {
+        $this->existing_file_content_hashes = null;
+        $this->new_file_content_hashes = [];
+
+        $this->file_contents_cache = [];
+        $this->file_content_hash = [];
+        $this->statements_cache = [];
+        $this->statements_cache_time = [];
+        return 0;
+    }
+
     public function saveFileContentHashes(): void
     {
     }