diff --git a/src/Differ/PatchDiffer.php b/src/Differ/PatchDiffer.php
index 204295e9..21d5ab6b 100644
--- a/src/Differ/PatchDiffer.php
+++ b/src/Differ/PatchDiffer.php
@@ -7,6 +7,7 @@
 use Nette\Utils\Strings;
 use SebastianBergmann\Diff\Differ;
 use Symplify\VendorPatches\Exception\ShouldNotHappenException;
+use Symplify\VendorPatches\Utils\FileSystemHelper;
 use Symplify\VendorPatches\ValueObject\OldAndNewFile;
 
 /**
@@ -50,7 +51,7 @@ public function diff(OldAndNewFile $oldAndNewFile): string
 
     private function resolveRelativeFilePath(string $beforeFilePath): string
     {
-        $match = Strings::match($beforeFilePath, self::LOCAL_PATH_REGEX);
+        $match = Strings::match(FileSystemHelper::normalizePath($beforeFilePath), self::LOCAL_PATH_REGEX);
 
         if (! isset($match['local_path'])) {
             throw new ShouldNotHappenException();
diff --git a/src/FileSystem/PathResolver.php b/src/FileSystem/PathResolver.php
index 4a202f19..f4de6682 100644
--- a/src/FileSystem/PathResolver.php
+++ b/src/FileSystem/PathResolver.php
@@ -6,6 +6,7 @@
 
 use Nette\Utils\Strings;
 use Symplify\VendorPatches\Exception\ShouldNotHappenException;
+use Symplify\VendorPatches\Utils\FileSystemHelper;
 use Webmozart\Assert\Assert;
 
 final class PathResolver
@@ -18,7 +19,7 @@ final class PathResolver
 
     public static function resolveVendorDirectory(string $filePath): string
     {
-        $match = Strings::match($filePath, self::VENDOR_PACKAGE_DIRECTORY_REGEX);
+        $match = Strings::match(FileSystemHelper::normalizePath($filePath), self::VENDOR_PACKAGE_DIRECTORY_REGEX);
         if (! isset($match['vendor_package_directory'])) {
             throw new ShouldNotHappenException('Could not resolve vendor package directory');
         }
diff --git a/src/Utils/FileSystemHelper.php b/src/Utils/FileSystemHelper.php
new file mode 100644
index 00000000..9db329c1
--- /dev/null
+++ b/src/Utils/FileSystemHelper.php
@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Symplify\VendorPatches\Utils;
+
+final class FileSystemHelper
+{
+    /**
+     * Converts backslashes to slashes.
+     */
+    public static function normalizePath(string $path): string
+    {
+        return str_replace('\\', '/', $path);
+    }
+}
diff --git a/tests/PatchFileFactory/PatchFileFactoryTest.php b/tests/PatchFileFactory/PatchFileFactoryTest.php
index e4e0a692..f2d2f573 100644
--- a/tests/PatchFileFactory/PatchFileFactoryTest.php
+++ b/tests/PatchFileFactory/PatchFileFactoryTest.php
@@ -6,6 +6,7 @@
 
 use Symplify\VendorPatches\PatchFileFactory;
 use Symplify\VendorPatches\Tests\AbstractTestCase;
+use Symplify\VendorPatches\Utils\FileSystemHelper;
 use Symplify\VendorPatches\ValueObject\OldAndNewFile;
 
 final class PatchFileFactoryTest extends AbstractTestCase
@@ -21,6 +22,6 @@ public function test(): void
         );
 
         $pathFilePath = $patchFileFactory->createPatchFilePath($oldAndNewFile, __DIR__ . '/Fixture');
-        $this->assertSame('patches/some-new-file-php.patch', $pathFilePath);
+        $this->assertSame('patches/some-new-file-php.patch', FileSystemHelper::normalizePath($pathFilePath));
     }
 }