diff --git a/src/File.php b/src/File.php
index 3f35de4..eeaed34 100644
--- a/src/File.php
+++ b/src/File.php
@@ -95,7 +95,7 @@ public function process(): string
 
         if ($this->enableZeroHeader) {
             // No calculation required
-        } elseif ($this->isSimulation() && $forecastSize) {
+        } elseif ($this->isSimulation() && $forecastSize !== null) {
             $this->uncompressedSize = $forecastSize;
             $this->compressedSize = $forecastSize;
         } else {
@@ -158,7 +158,7 @@ private function forecastSize(): ?int
         if ($this->compressionMethod !== CompressionMethod::STORE) {
             return null;
         }
-        if ($this->exactSize) {
+        if ($this->exactSize !== null) {
             return $this->exactSize;
         }
         $fstat = fstat($this->unpackStream());
@@ -350,7 +350,7 @@ private function readStream(bool $send): void
             }
         }
 
-        if ($this->exactSize && $this->uncompressedSize !== $this->exactSize) {
+        if ($this->exactSize !== null && $this->uncompressedSize !== $this->exactSize) {
             throw new FileSizeIncorrectException(expectedSize: $this->exactSize, actualSize: $this->uncompressedSize);
         }
 
diff --git a/src/ZipStream.php b/src/ZipStream.php
index 195a4bf..8a06fec 100644
--- a/src/ZipStream.php
+++ b/src/ZipStream.php
@@ -330,7 +330,8 @@ public function addFileFromPath(
             throw new FileNotReadableException($path);
         }
 
-        if ($fileTime = filemtime($path)) {
+        $fileTime = filemtime($path);
+        if ($fileTime !== false) {
             $lastModificationDateTime ??= (new DateTimeImmutable())->setTimestamp($fileTime);
         }
 
@@ -581,7 +582,7 @@ public function addFileFromCallback(
                 if ($maxSize !== null && fwrite($stream, $data, $maxSize) === false) {
                     // @codeCoverageIgnoreStart
                     throw new ResourceActionException('fwrite', $stream);
-                // @codeCoverageIgnoreEnd
+                    // @codeCoverageIgnoreEnd
                 } elseif (fwrite($stream, $data) === false) {
                     // @codeCoverageIgnoreStart
                     throw new ResourceActionException('fwrite', $stream);
@@ -823,7 +824,7 @@ private function sendHttpHeaders(): void
         // grab content disposition
         $disposition = $this->contentDisposition;
 
-        if ($this->outputName) {
+        if ($this->outputName !== null) {
             // Various different browsers dislike various characters here. Strip them all for safety.
             $safeOutput = trim(str_replace(['"', "'", '\\', ';', "\n", "\r"], '', $this->outputName));
 
diff --git a/test/ResourceStream.php b/test/ResourceStream.php
index c33d02b..752a1a3 100644
--- a/test/ResourceStream.php
+++ b/test/ResourceStream.php
@@ -58,7 +58,7 @@ public function seek(int $offset, int $whence = SEEK_SET): void
 
     public function isSeekable(): bool
     {
-        return (bool)$this->getMetadata('seekable');
+        return (bool) $this->getMetadata('seekable');
     }
 
     public function getMetadata(?string $key = null)
diff --git a/test/Util.php b/test/Util.php
index 2fd3517..e39f5bf 100644
--- a/test/Util.php
+++ b/test/Util.php
@@ -106,7 +106,7 @@ protected function getTmpDir(): string
     protected function getRecursiveFileList(string $path, bool $includeDirectories = false): array
     {
         $data = [];
-        $path = (string)realpath($path);
+        $path = (string) realpath($path);
         $files = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($path));
 
         $pathLen = strlen($path);
diff --git a/test/ZipStreamTest.php b/test/ZipStreamTest.php
index fbbe533..c5fc6e9 100644
--- a/test/ZipStreamTest.php
+++ b/test/ZipStreamTest.php
@@ -1161,7 +1161,7 @@ private function addLargeFileFileFromPath(CompressionMethod $compressionMethod,
 
         [$tmpExample, $streamExample] = $this->getTmpFileStream();
         for ($i = 0; $i <= 10000; $i++) {
-            fwrite($streamExample, sha1((string)$i));
+            fwrite($streamExample, sha1((string) $i));
             if ($i % 100 === 0) {
                 fwrite($streamExample, "\n");
             }