diff --git a/dill/_utils.py b/dill/_utils.py
index 0d9d86e2..0aaf65a5 100644
--- a/dill/_utils.py
+++ b/dill/_utils.py
@@ -166,11 +166,12 @@ def __repr__(self):
 Filter = Union[str, Pattern[str], int, type, FilterFunction]
 Rule = Tuple[RuleType, Union[Filter, Iterable[Filter]]]
 
-def _iter(filters):
-    if isinstance(filters, str):
+def _iter(obj):
+    """return iterator of object if it's not a string"""
+    if isinstance(obj, (str, bytes)):
         return None
     try:
-        return iter(filters)
+        return iter(obj)
     except TypeError:
         return None
 
@@ -199,7 +200,7 @@ def _match_type(self, filter: Filter) -> Tuple[filter, str]:
             else:
                 filter = re.compile(filter)
                 field = 'regexes'
-        elif filter_type is re.Pattern:
+        elif filter_type is re.Pattern and type(filter.pattern) is str:
             field = 'regexes'
         elif filter_type is int:
             field = 'ids'
diff --git a/dill/tests/test_filtering.py b/dill/tests/test_filtering.py
index 259b5fd6..3bcc0c9c 100644
--- a/dill/tests/test_filtering.py
+++ b/dill/tests/test_filtering.py
@@ -11,9 +11,64 @@
 import dill
 from dill import _dill
 from dill.session import (
-    EXCLUDE, INCLUDE, FilterRules, RuleType, ipython_filter, size_filter, settings
+    EXCLUDE, INCLUDE, FilterRules, FilterSet, RuleType, ipython_filter, size_filter, settings
 )
 
+def test_filterset():
+    import re
+
+    name = 'test'
+    regex1 = re.compile(r'\w+\d+')
+    regex2 = r'_\w+'
+    id_ = id(FilterSet)
+    type1 = FilterSet
+    type2 = 'type:List'
+    func = lambda obj: obj.name == 'Arthur'
+
+    empty_filters = FilterSet()
+    assert bool(empty_filters) is False
+    assert len(empty_filters) == 0
+    assert len([*empty_filters]) == 0
+
+    # also tests add() and __ior__() for non-FilterSet other
+    filters = FilterSet._from_iterable([name, regex1, regex2, id_, type1, type2, func])
+    assert filters.names == {name}
+    assert filters.regexes == {regex1, re.compile(regex2)}
+    assert filters.ids == {id_}
+    assert filters.types == {type1, list}
+    assert filters.funcs == {func}
+
+    assert bool(filters) is True
+    assert len(filters) == 7
+    assert all(x in filters for x in [name, regex1, id_, type1, func])
+
+    try:
+        filters.add(re.compile(b'an 8-bit string regex'))
+    except ValueError:
+        pass
+    else:
+        raise AssertionError("adding invalid filter should raise error")
+
+    filters_copy = filters.copy()
+    for field in FilterSet._fields:
+        original, copy = getattr(filters, field), getattr(filters_copy, field)
+        assert copy is not original
+        assert copy == original
+
+    filters.remove(re.compile(regex2))
+    assert filters.regexes == {regex1}
+    filters.discard(list)
+    filters.discard(list)  # should not raise error
+    assert filters.types == {type1}
+    assert [*filters] == [name, regex1, id_, type1, func]
+
+    # also tests __ior__() for FilterSet other
+    filters.update(filters_copy)
+    assert filters.types == {type1, list}
+
+    filters.clear()
+    assert len(filters) == 0
+
 NS = {
     'a': 1,
     'aa': 2,
@@ -184,6 +239,7 @@ def test_size_filter():
     assert did_exclude(NS_copy, filter_size, excluded_subset={'large'})
 
 if __name__ == '__main__':
+    test_filterset()
     test_basic_filtering()
     test_exclude_include()
     test_add_type()