diff --git a/lib/Ansel.php b/lib/Ansel.php
index 161bd5fa..c87ab456 100644
--- a/lib/Ansel.php
+++ b/lib/Ansel.php
@@ -1,5 +1,7 @@
 <?php
 
+use Horde\Compress\CompressFactory;
+
 /**
  * Ansel Base Class.
  *
@@ -830,8 +832,8 @@ public static function downloadImagesAsZip($gallery = null, $images = array())
                                 'name' => $image->filename);
         }
 
-        $zip = Horde_Compress::factory('zip');
-        $body = $zip->compress($zipfiles);
+        $zip = (new CompressFactory())->create('zip');
+        $body = $zip->compressFiles($zipfiles);
         if (!empty($gallery)) {
             $filename = (!empty($slug) ? $slug : $gallery->id) . '.zip';
         } else {
diff --git a/lib/View/Upload.php b/lib/View/Upload.php
index e414cd80..6213e13c 100644
--- a/lib/View/Upload.php
+++ b/lib/View/Upload.php
@@ -1,5 +1,9 @@
 <?php
 
+use Horde\Compress\CompressFactory;
+use Horde\Compress\Driver\Zip as CompressZip;
+use Horde\Compress\Exception as CompressException;
+
 /**
  * Copyright 2010-2017 Horde LLC (http://www.horde.org/)
  *
@@ -533,9 +537,9 @@ private function _handleZip($filename)
 
             /* Get list of images */
             try {
-                $zip = Horde_Compress::factory('zip');
-                $files = $zip->decompress($data, array('action' => Horde_Compress_Zip::ZIP_LIST));
-            } catch (Horde_Compress_Exception $e) {
+                $zip = (new CompressFactory())->create('zip');
+                $files = $zip->decompress($data, array('action' => CompressZip::ZIP_LIST));
+            } catch (CompressException $e) {
                 throw new Ansel_Exception($e);
             }
 
@@ -547,14 +551,15 @@ private function _handleZip($filename)
 
                 /* Extract the image */
                 try {
-                    $zdata = $zip->decompress(
+                    $result = $zip->decompress(
                         $data,
                         array(
-                            'action' => Horde_Compress_Zip::ZIP_DATA,
+                            'action' => CompressZip::ZIP_DATA,
                             'info' => $files,
                             'key' => $key)
                     );
-                } catch (Horde_Compress_Exception $e) {
+                    $zdata = is_array($result) ? $result['data'] : $result;
+                } catch (CompressException $e) {
                     throw new Ansel_Exception($e);
                 }
 
diff --git a/test/Ansel/AnselCompressTest.php b/test/Ansel/AnselCompressTest.php
new file mode 100644
index 00000000..a2a53385
--- /dev/null
+++ b/test/Ansel/AnselCompressTest.php
@@ -0,0 +1,128 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Horde\Ansel\Test;
+
+use Horde\Compress\CompressFactory;
+use Horde\Compress\Driver\Zip;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Tests the ZIP compress/decompress contract as used by Ansel.
+ *
+ * Ansel uses two patterns:
+ * 1. Compress: collect files → compressFiles() → raw ZIP string for download
+ * 2. Decompress: ZIP_LIST for listing, ZIP_DATA for raw file content passed to addImage()
+ */
+class AnselCompressTest extends TestCase
+{
+    /**
+     * Ansel.php pattern: compress an array of ['data','name'] into a ZIP string.
+     * The caller sends this string directly as a download body with strlen().
+     */
+    public function testCompressReturnsNonEmptyString(): void
+    {
+        $zip = (new CompressFactory())->create('zip');
+
+        $files = [
+            ['data' => 'image-binary-data-1', 'name' => 'photo1.jpg'],
+            ['data' => 'image-binary-data-2', 'name' => 'photo2.jpg'],
+        ];
+
+        $body = $zip->compressFiles($files);
+
+        $this->assertIsString($body);
+        $this->assertNotEmpty($body);
+        $this->assertGreaterThan(0, strlen($body));
+    }
+
+    /**
+     * View/Upload.php pattern: decompress ZIP_LIST returns array of entries
+     * with 'name' key that the caller uses to filter meta files.
+     */
+    public function testDecompressListReturnsEntriesWithNames(): void
+    {
+        $zip = (new CompressFactory())->create('zip');
+
+        $files = [
+            ['data' => 'img-a', 'name' => 'gallery/photo_a.png'],
+            ['data' => 'img-b', 'name' => 'gallery/photo_b.png'],
+            ['data' => 'meta', 'name' => '__MACOSX/.DS_Store'],
+        ];
+
+        $archive = $zip->compressFiles($files);
+        $listing = $zip->decompress($archive, [
+            'action' => Zip::ZIP_LIST,
+        ]);
+
+        $this->assertIsArray($listing);
+        $this->assertCount(3, $listing);
+        $this->assertEquals('gallery/photo_a.png', $listing[0]['name']);
+        $this->assertEquals('gallery/photo_b.png', $listing[1]['name']);
+        $this->assertEquals('__MACOSX/.DS_Store', $listing[2]['name']);
+    }
+
+    /**
+     * View/Upload.php pattern: decompress ZIP_DATA returns file content.
+     * The PSR-4 API returns ['data' => string], so the caller unwraps it.
+     * The addImage() call receives a raw string either way.
+     */
+    public function testDecompressDataReturnsContent(): void
+    {
+        $zip = (new CompressFactory())->create('zip');
+
+        $originalContent = random_bytes(256);
+        $files = [
+            ['data' => $originalContent, 'name' => 'test_image.jpg'],
+        ];
+
+        $archive = $zip->compressFiles($files);
+        $listing = $zip->decompress($archive, [
+            'action' => Zip::ZIP_LIST,
+        ]);
+
+        $result = $zip->decompress($archive, [
+            'action' => Zip::ZIP_DATA,
+            'info' => $listing,
+            'key' => 0,
+        ]);
+
+        // PSR-4 returns ['data' => string]; caller unwraps with is_array check.
+        $zdata = is_array($result) ? $result['data'] : $result;
+        $this->assertIsString($zdata);
+        $this->assertEquals($originalContent, $zdata);
+    }
+
+    /**
+     * Round-trip: compress multiple files then extract each one individually.
+     * Proves the full cycle matches what Ansel does in Upload.php.
+     */
+    public function testRoundTripMultipleFiles(): void
+    {
+        $zip = (new CompressFactory())->create('zip');
+
+        $inputFiles = [
+            ['data' => 'content-alpha', 'name' => 'alpha.dat'],
+            ['data' => 'content-beta', 'name' => 'beta.dat'],
+            ['data' => 'content-gamma', 'name' => 'gamma.dat'],
+        ];
+
+        $archive = $zip->compressFiles($inputFiles);
+        $listing = $zip->decompress($archive, [
+            'action' => Zip::ZIP_LIST,
+        ]);
+
+        $this->assertCount(3, $listing);
+
+        foreach ($inputFiles as $key => $input) {
+            $result = $zip->decompress($archive, [
+                'action' => Zip::ZIP_DATA,
+                'info' => $listing,
+                'key' => $key,
+            ]);
+            $extracted = is_array($result) ? $result['data'] : $result;
+            $this->assertEquals($input['data'], $extracted, "File at key $key mismatch");
+        }
+    }
+}