diff --git a/apps/theming/lib/IconBuilder.php b/apps/theming/lib/IconBuilder.php
index 4b9ab1e130d48..6d4b84098b156 100644
--- a/apps/theming/lib/IconBuilder.php
+++ b/apps/theming/lib/IconBuilder.php
@@ -53,6 +53,9 @@ public function __construct(
 	 * @return string|false image blob
 	 */
 	public function getFavicon($app) {
+		if (!$this->themingDefaults->shouldReplaceIcons()) {
+			return false;
+		}
 		try {
 			$favicon = new Imagick();
 			$favicon->setFormat("ico");
diff --git a/apps/theming/tests/IconBuilderTest.php b/apps/theming/tests/IconBuilderTest.php
index 8fc0d3b62b785..1b02b74fce2a8 100644
--- a/apps/theming/tests/IconBuilderTest.php
+++ b/apps/theming/tests/IconBuilderTest.php
@@ -151,12 +151,15 @@ public function testGetFavicon($app, $color, $file) {
 			->willReturn($color);
 
 		$expectedIcon = new \Imagick(realpath(dirname(__FILE__)). "/data/" . $file);
+		$actualIcon = $this->iconBuilder->getFavicon($app);
+
 		$icon = new \Imagick();
-		$icon->readImageBlob($this->iconBuilder->getFavicon($app));
+		$icon->setFormat('ico');
+		$icon->readImageBlob($actualIcon);
 
 		$this->assertEquals(true, $icon->valid());
-		$this->assertEquals(32, $icon->getImageWidth());
-		$this->assertEquals(32, $icon->getImageHeight());
+		$this->assertEquals(128, $icon->getImageWidth());
+		$this->assertEquals(128, $icon->getImageHeight());
 		$icon->destroy();
 		$expectedIcon->destroy();
 		// FIXME: We may need some comparison of the generated and the test images