diff --git a/src/Psalm/Internal/Provider/FileProvider.php b/src/Psalm/Internal/Provider/FileProvider.php
index b5e5443fab0..42321b6098c 100644
--- a/src/Psalm/Internal/Provider/FileProvider.php
+++ b/src/Psalm/Internal/Provider/FileProvider.php
@@ -100,7 +100,7 @@ public function removeTemporaryFileChanges(string $file_path): void
 
     public function openFile(string $file_path): void
     {
-        $this->getContents($file_path, true);
+        $this->open_files[strtolower($file_path)] = $this->getContents($file_path, true);
     }
 
     public function isOpen(string $file_path): bool