diff --git a/src/File/FileReader.php b/src/File/FileReader.php
index 5bc5220ae7..40b65477b9 100644
--- a/src/File/FileReader.php
+++ b/src/File/FileReader.php
@@ -4,16 +4,23 @@
 
 use function file_get_contents;
 use function is_file;
+use function stream_resolve_include_path;
 
 class FileReader
 {
 
 	public static function read(string $fileName): string
 	{
-		if (!is_file($fileName)) {
-			throw new CouldNotReadFileException($fileName);
+		$path = $fileName;
+
+		if (!is_file($path)) {
+			$path = stream_resolve_include_path($fileName);
+
+			if ($path === false) {
+				throw new CouldNotReadFileException($fileName);
+			}
 		}
-		$contents = @file_get_contents($fileName);
+		$contents = @file_get_contents($path);
 		if ($contents === false) {
 			throw new CouldNotReadFileException($fileName);
 		}
diff --git a/src/Reflection/BetterReflection/SourceLocator/FileReadTrapStreamWrapper.php b/src/Reflection/BetterReflection/SourceLocator/FileReadTrapStreamWrapper.php
index 61007436a5..10e2f78e54 100644
--- a/src/Reflection/BetterReflection/SourceLocator/FileReadTrapStreamWrapper.php
+++ b/src/Reflection/BetterReflection/SourceLocator/FileReadTrapStreamWrapper.php
@@ -3,7 +3,9 @@
 namespace PHPStan\Reflection\BetterReflection\SourceLocator;
 
 use PHPStan\ShouldNotHappenException;
+use function is_file;
 use function stat;
+use function stream_resolve_include_path;
 use function stream_wrapper_register;
 use function stream_wrapper_restore;
 use function stream_wrapper_unregister;
@@ -94,11 +96,15 @@ public static function withStreamWrapperOverride(
 	 */
 	public function stream_open($path, $mode, $options, &$openedPath): bool
 	{
-		self::$autoloadLocatedFiles[] = $path;
+		$exists = is_file($path) || (stream_resolve_include_path($path) !== false);
+
+		if ($exists) {
+			self::$autoloadLocatedFiles[] = $path;
+		}
 		$this->readFromFile = false;
 		$this->seekPosition = 0;
 
-		return true;
+		return $exists;
 	}
 
 	/**