diff --git a/src/Factory/StreamFactory.php b/src/Factory/StreamFactory.php
index 07b92b2..df74cff 100644
--- a/src/Factory/StreamFactory.php
+++ b/src/Factory/StreamFactory.php
@@ -53,29 +53,35 @@ public function createStreamFromFile(
         string $mode = 'r',
         StreamInterface $cache = null
     ): StreamInterface {
-        // When fopen fails, PHP normally raises a warning. Add an error
+        // When fopen fails, PHP 7 normally raises a warning. Add an error
         // handler to check for errors and throw an exception instead.
+        // On PHP 8, exceptions are thrown.
         $exc = null;
 
-        set_error_handler(function (int $errno, string $errstr) use ($filename, $mode, &$exc) {
+        // Would not be initialized if fopen throws on PHP >= 8.0
+        $resource = null;
+
+        $errorHandler = function (string $errorMessage) use ($filename, $mode, &$exc) {
             $exc = new RuntimeException(sprintf(
                 'Unable to open %s using mode %s: %s',
                 $filename,
                 $mode,
-                $errstr
+                $errorMessage
             ));
+        };
+
+        set_error_handler(function (int $errno, string $errstr) use ($errorHandler) {
+            $errorHandler($errstr);
         });
 
         try {
             $resource = fopen($filename, $mode);
+        // @codeCoverageIgnoreStart
+        // (Can only be executed in PHP >= 8.0)
         } catch (\ValueError $exception) {
-            throw new RuntimeException(sprintf(
-                'Unable to open %s using mode %s: %s',
-                $filename,
-                $mode,
-                $exception->getMessage()
-            ));
+            $errorHandler($exception->getMessage());
         }
+        // @codeCoverageIgnoreEnd
         restore_error_handler();
 
         if ($exc) {