diff --git a/src/Files/DummyFile.php b/src/Files/DummyFile.php
index 3275bf0920..601430301d 100644
--- a/src/Files/DummyFile.php
+++ b/src/Files/DummyFile.php
@@ -38,7 +38,7 @@ public function __construct($content, Ruleset $ruleset, Config $config)
         // This is done by including: phpcs_input_file: [file path]
         // as the first line of content.
         $path = 'STDIN';
-        if ($content !== null) {
+        if ($content !== '') {
             if (substr($content, 0, 17) === 'phpcs_input_file:') {
                 $eolPos   = strpos($content, $this->eolChar);
                 $filename = trim(substr($content, 17, ($eolPos - 17)));
diff --git a/src/Runner.php b/src/Runner.php
index 03238cd59d..253ec91f9f 100644
--- a/src/Runner.php
+++ b/src/Runner.php
@@ -732,7 +732,7 @@ private function processChildProcs($childProcs)
 
                         if (isset($childOutput) === false) {
                             // The child process died, so the run has failed.
-                            $file = new DummyFile(null, $this->ruleset, $this->config);
+                            $file = new DummyFile('', $this->ruleset, $this->config);
                             $file->setErrorCounts(1, 0, 0, 0);
                             $this->printProgress($file, $totalBatches, $numProcessed);
                             $success = false;
@@ -756,7 +756,7 @@ private function processChildProcs($childProcs)
                         }
 
                         // Fake a processed file so we can print progress output for the batch.
-                        $file = new DummyFile(null, $this->ruleset, $this->config);
+                        $file = new DummyFile('', $this->ruleset, $this->config);
                         $file->setErrorCounts(
                             $childOutput['totalErrors'],
                             $childOutput['totalWarnings'],