diff --git a/lib/Classifiers/Classifier.php b/lib/Classifiers/Classifier.php
index a1f9de96..24ee7809 100644
--- a/lib/Classifiers/Classifier.php
+++ b/lib/Classifiers/Classifier.php
@@ -233,7 +233,7 @@ private function getConvertedFilePath(Node $file): string {
 		}
 		$path = $file->getStorage()->getLocalFile($file->getInternalPath());
 
-		if ($path === false) {
+		if (!is_string($path)) {
 			throw new NotFoundException();
 		}
 
diff --git a/psalm-baseline.xml b/psalm-baseline.xml
index 15df84d4..a3b9a63e 100644
--- a/psalm-baseline.xml
+++ b/psalm-baseline.xml
@@ -113,6 +113,9 @@
     </InvalidScalarArgument>
   </file>
   <file src="lib/Classifiers/Classifier.php">
+    <DocblockTypeContradiction occurrences="1">
+      <code>$preview === false</code>
+    </DocblockTypeContradiction>
     <MixedAssignment occurrences="1">
       <code>$results</code>
     </MixedAssignment>