diff --git a/apps/theming/css/theming.scss b/apps/theming/css/theming.scss
index 339bf8a58b..22e3bdc0d9 100644
--- a/apps/theming/css/theming.scss
+++ b/apps/theming/css/theming.scss
@@ -11,7 +11,7 @@
 }
 
 /* invert header icons on bright background */
-@if (lightness($color-primary) > 50) {
+@if (lightness($color-primary) > 55) {
 	.searchbox input[type="search"] {
 		background: transparent url('../../../core/img/actions/search.svg') no-repeat 6px center;
 	}
diff --git a/apps/theming/lib/Util.php b/apps/theming/lib/Util.php
index f0e8fd92ca..83d8c7aae4 100644
--- a/apps/theming/lib/Util.php
+++ b/apps/theming/lib/Util.php
@@ -62,7 +62,7 @@ class Util {
 	 */
 	public function invertTextColor($color) {
 		$l = $this->calculateLuminance($color);
-		if($l>0.5) {
+		if($l>0.55) {
 			return true;
 		} else {
 			return false;