diff --git a/lib/private/Preview/Generator.php b/lib/private/Preview/Generator.php
index dcd4ccd130c80..5a96c69502c98 100644
--- a/lib/private/Preview/Generator.php
+++ b/lib/private/Preview/Generator.php
@@ -162,6 +162,12 @@ public function getPreview(File $file, $width = -1, $height = -1, $crop = false,
 			throw new NotFoundException('Cached preview size 0, invalid!');
 		}
 
+		// Free memory being used by the embedded image resource.  Without this the image is kept in memory indefinitely.
+		// Garbage Collection does NOT free this memory.  We have to do it ourselves.
+		if ($maxPreviewImage instanceof \OC_Image) {
+			$maxPreviewImage->destroy();
+		}
+
 		return $preview;
 	}
 
diff --git a/tests/lib/Preview/GeneratorTest.php b/tests/lib/Preview/GeneratorTest.php
index cfb78a05da5e8..256c6d5ff773d 100644
--- a/tests/lib/Preview/GeneratorTest.php
+++ b/tests/lib/Preview/GeneratorTest.php
@@ -31,7 +31,6 @@
 use OCP\Files\SimpleFS\ISimpleFile;
 use OCP\Files\SimpleFS\ISimpleFolder;
 use OCP\IConfig;
-use OCP\IImage;
 use OCP\IPreview;
 use OCP\Preview\IProvider;
 use OCP\Preview\IProviderV2;
@@ -184,7 +183,7 @@ public function testGetNewPreview() {
 				$this->fail('Unexpected provider requested');
 			}));
 
-		$image = $this->createMock(IImage::class);
+		$image = $this->createMock(\OC_Image::class);
 		$image->method('width')->willReturn(2048);
 		$image->method('height')->willReturn(2048);
 		$image->method('valid')->willReturn(true);