diff --git a/tests/BinTestCase.php b/tests/BinTestCase.php
index aefc344..35bf374 100644
--- a/tests/BinTestCase.php
+++ b/tests/BinTestCase.php
@@ -36,6 +36,9 @@ protected function runCommand(
             fclose($pipe);
         }
 
+        self::assertNotFalse($output);
+        self::assertNotFalse($errorOutput);
+
         $extraInfo = "Output was:\n" . $output . "\nError was:\n" . $errorOutput . "\n";
 
         if ($expectedOutputContains !== null) {