diff --git a/src/app/tk_tools.py b/src/app/tk_tools.py
index 606e4ab69..94054d324 100644
--- a/src/app/tk_tools.py
+++ b/src/app/tk_tools.py
@@ -92,6 +92,7 @@ def set_window_icon(window: Union[tk.Toplevel, tk.Tk]) -> None:
 
     LISTBOX_BG_SEL_COLOR = 'blue'
     LISTBOX_BG_COLOR = 'white'
+    LABEL_HIGHLIGHT_BG = '#5AD2D2'
 
 # Some events differ on different systems, so define them here.
 if utils.MAC: