diff --git a/traits/ctraits.c b/traits/ctraits.c
index 70331b23..8faa73d7 100644
--- a/traits/ctraits.c
+++ b/traits/ctraits.c
@@ -148,7 +148,7 @@ call_notifiers(
 +----------------------------------------------------------------------------*/
 
 /* The default_value of the trait is the default value */
-#define CONSTANT_DEFAULT_VALUE 0
+#define CONSTANT_DEFAULT_VALUE 7
 
 /* The default_value of the trait is Missing */
 #define MISSING_DEFAULT_VALUE 1
@@ -174,7 +174,7 @@ call_notifiers(
    where *callable* is a callable, *args* is a tuple, and *kw* is either a
    dictionary or None. The default value is the result obtained by invoking
   ``callable(\*args, \*\*kw)`` */
-#define CALLABLE_AND_ARGS_DEFAULT_VALUE 7
+#define CALLABLE_AND_ARGS_DEFAULT_VALUE 15
 
 /* The default_value is a callable. The default value is the result obtained
    by invoking *default_value*(*object*), where *object* is the object
diff --git a/traits/trait_types.py b/traits/trait_types.py
index 777d0e2b..b7874ead 100644
--- a/traits/trait_types.py
+++ b/traits/trait_types.py
@@ -4028,7 +4028,7 @@ class Union(TraitType):
         if 'default_value' in metadata:
             default_value = metadata.pop("default_value")
         else:
-            first_default_value, first_default_value_type = (
+            first_default_value_type, first_default_value = (
                 self.list_ctrait_instances[0].default_value())
 
             if first_default_value_type == DefaultValue.constant: