diff --git a/generated/filesystem.php b/generated/filesystem.php
index 28b4a1c6..80ad5564 100644
--- a/generated/filesystem.php
+++ b/generated/filesystem.php
@@ -449,6 +449,26 @@ function fileowner(string $filename): int
 }
 
 
+/**
+ * Gets the size for the given file.
+ *
+ * @param string $filename Path to the file.
+ * @return int Returns the size of the file in bytes, or FALSE (and generates an error
+ * of level E_WARNING) in case of an error.
+ * @throws FilesystemException
+ *
+ */
+function filesize(string $filename): int
+{
+    error_clear_last();
+    $result = \filesize($filename);
+    if ($result === false) {
+        throw FilesystemException::createFromPhpError();
+    }
+    return $result;
+}
+
+
 /**
  * flock allows you to perform a simple reader/writer
  * model which can be used on virtually every platform (including most Unix
diff --git a/generated/functionsList.php b/generated/functionsList.php
index 71b2fdd0..2c41fd46 100644
--- a/generated/functionsList.php
+++ b/generated/functionsList.php
@@ -145,6 +145,7 @@
     'fileinode',
     'filemtime',
     'fileowner',
+    'filesize',
     'flock',
     'fopen',
     'fputcsv',
diff --git a/generator/src/DocPage.php b/generator/src/DocPage.php
index 3be73c23..ddcc1a85 100644
--- a/generator/src/DocPage.php
+++ b/generator/src/DocPage.php
@@ -48,6 +48,9 @@ public function detectFalsyFunction(): bool
         if (preg_match('/&date.datetime.return.modifiedobjectorfalseforfailure;/m', $file)) {
             return true;
         }
+        if (preg_match('/ or &false; \\(and generates an error/m', $file)) {
+            return true;
+        }
 
         return false;
     }
diff --git a/generator/tests/DocPageTest.php b/generator/tests/DocPageTest.php
index c9b483a1..e7635399 100644
--- a/generator/tests/DocPageTest.php
+++ b/generator/tests/DocPageTest.php
@@ -11,7 +11,7 @@ public function testDetectFalsyFunction() {
         $implode = new DocPage(__DIR__ . '/../doc/doc-en/en/reference/strings/functions/implode.xml');
         $getCwd = new DocPage(__DIR__ . '/../doc/doc-en/en/reference/dir/functions/getcwd.xml');
         $setTime = new DocPage(__DIR__ . '/../doc/doc-en/en/reference/datetime/datetime/settime.xml');
-        $filesize = new DocPage(__DIR__ . '/../doc/doc-en/en/reference/datetime/filesystem/filesize.xml');
+        $filesize = new DocPage(__DIR__ . '/../doc/doc-en/en/reference/filesystem/functions/filesize.xml');
 
         $this->assertTrue($pregMatch->detectFalsyFunction());
         $this->assertFalse($implode->detectFalsyFunction());
diff --git a/rector-migrate.yml b/rector-migrate.yml
index a5cd796c..890b66d1 100644
--- a/rector-migrate.yml
+++ b/rector-migrate.yml
@@ -146,6 +146,7 @@ services:
       fileinode: 'Safe\fileinode'
       filemtime: 'Safe\filemtime'
       fileowner: 'Safe\fileowner'
+      filesize: 'Safe\filesize'
       flock: 'Safe\flock'
       fopen: 'Safe\fopen'
       fputcsv: 'Safe\fputcsv'