diff --git a/Flow.Launcher.Plugin/SharedModels/ThemeData.cs b/Flow.Launcher.Plugin/SharedModels/ThemeData.cs
index 322985f3a..093e1ee8e 100644
--- a/Flow.Launcher.Plugin/SharedModels/ThemeData.cs
+++ b/Flow.Launcher.Plugin/SharedModels/ThemeData.cs
@@ -43,6 +43,8 @@ public class ThemeData
     {
         if (left is null && right is null)
             return true;
+        if (left is null || right is null)
+            return false;
         return left.Equals(right);
     }