diff --git a/Source/src/WixSharp/ProjectValidator.cs b/Source/src/WixSharp/ProjectValidator.cs
index 042fc0c2..ce0341e4 100644
--- a/Source/src/WixSharp/ProjectValidator.cs
+++ b/Source/src/WixSharp/ProjectValidator.cs
@@ -112,7 +112,7 @@ public static void Validate(Project project)
 
                 if (invalidAspectRatio)
                     throw new ValidationException(
-                        "Project.BackgroundImage has incompatible (with ManagedUI default dialogs) aspect ratio. The expected ratio is close to 492x312. " +
+                        "Project.BackgroundImage has incompatible (with ManagedUI default dialogs) aspect ratio. The expected ratio is close to W(156)/H(312). " +
                         "The background image in ManagedUI dialogs is left-docked at runtime and if it's too wide it can push away (to right) " +
                         "the all other UI elements. " +
                         "You can suppress image validation by setting Project.ValidateBackgroundImage to 'false'.");