diff --git a/tools/demo-gui/demo-gui/sof_demo_gui.py b/tools/demo-gui/demo-gui/sof_demo_gui.py
index d4a49a8ad333..3f18287adf2a 100644
--- a/tools/demo-gui/demo-gui/sof_demo_gui.py
+++ b/tools/demo-gui/demo-gui/sof_demo_gui.py
@@ -63,7 +63,7 @@ def apply_css(self):
             color: #FFFFFF;
         }
         headerbar.titlebar {
-            background: #2C3E50;
+            background-color: #2C3E50;
         }
         """
         css_provider.load_from_data(css.encode('utf-8'))