diff --git a/tap/tap.py b/tap/tap.py
index 4d76355..694ed94 100644
--- a/tap/tap.py
+++ b/tap/tap.py
@@ -408,7 +408,7 @@ def as_dict(self) -> Dict[str, Any]:
 
         return {var: getattr(self, var) for var in self._get_argument_names()}
 
-    def from_dict(self, args_dict: Dict[str, Any]) -> None:
+    def from_dict(self, args_dict: Dict[str, Any], skip_unsettable: bool = False) -> None:
         """Loads arguments from a dictionary, ensuring all required arguments are set.
 
         :param args_dict: A dictionary from argument names to the values of the arguments.
@@ -426,8 +426,11 @@ def from_dict(self, args_dict: Dict[str, Any]) -> None:
         for key, value in args_dict.items():
             try:
                 setattr(self, key, value)
-            except AttributeError as e:
-                warnings.warn(e)
+            except AttributeError:
+                if not skip_unsettable:
+                    raise AttributeError(f'Cannot set attribute "{key}" to "{value}." '
+                                         f'To skip arguments that cannot be set \n'
+                                         f'"skip_unsettable = True" \n')
 
         self._parsed = True
 
diff --git a/tap/utils.py b/tap/utils.py
index 4f75a5c..2158f1b 100644
--- a/tap/utils.py
+++ b/tap/utils.py
@@ -343,10 +343,10 @@ def fix_py36_copy(func: Callable) -> Callable:
     if sys.version_info[:2] != (3, 6):
         return func
 
-    re_type = type(re.compile(''))
 
     @wraps(func)
     def wrapper(*args, **kwargs):
+        re_type = type(re.compile(''))
         has_prev_val = re_type in copy._deepcopy_dispatch
         prev_val = copy._deepcopy_dispatch.get(re_type, None)
         copy._deepcopy_dispatch[type(re.compile(''))] = lambda r, _: r
@@ -355,8 +355,6 @@ def wrapper(*args, **kwargs):
 
         if has_prev_val:
             copy._deepcopy_dispatch[re_type] = prev_val
-        else:
-            del copy._deepcopy_dispatch[re_type]
 
         return result
 
diff --git a/tests/test_integration.py b/tests/test_integration.py
index f16bf7a..cc95121 100644
--- a/tests/test_integration.py
+++ b/tests/test_integration.py
@@ -900,6 +900,7 @@ class SimpleFromDictTap(Tap):
 
 
 class TestStoringTap(TestCase):
+
     def test_save_load_simple(self):
         class SimpleSaveLoadTap(Tap):
             a: str