diff --git a/Terminal.Gui/Configuration/ConfigurationManager.cs b/Terminal.Gui/Configuration/ConfigurationManager.cs
index 73c770c751..ff1d021b83 100644
--- a/Terminal.Gui/Configuration/ConfigurationManager.cs
+++ b/Terminal.Gui/Configuration/ConfigurationManager.cs
@@ -199,9 +199,14 @@ internal static void Initialize ()
 
             foreach (KeyValuePair<string, ConfigProperty> hardCodedProperty in _hardCodedConfigPropertyCache)
             {
-                // Set the PropertyValue to the hard coded value
+                // Set the PropertyValue to the hard coded value.
+                // Deep-clone the value to ensure the cache stores independent copies of reference types
+                // (e.g. Dictionary<,>). Without cloning, in-place mutations to a static property like
+                // Application.DefaultKeyBindings (e.g. dict[cmd] = ...) would silently corrupt the
+                // cached "hard-coded default", causing test-order-dependent failures.
                 hardCodedProperty.Value.Immutable = false;
                 hardCodedProperty.Value.UpdateToCurrentValue ();
+                hardCodedProperty.Value.PropertyValue = DeepCloner.DeepClone (hardCodedProperty.Value.PropertyValue);
                 hardCodedProperty.Value.Immutable = true;
             }
         }