diff --git a/tests/test_enum.py b/tests/test_enum.py
index b8a3b71c..dcc549dd 100644
--- a/tests/test_enum.py
+++ b/tests/test_enum.py
@@ -105,6 +105,22 @@ def goodbye(self):
         assert s.is_ONE()
         assert s.message == 'Goodbye'
 
+    def test_str_enum(self):
+        class States(str, enum.Enum):
+            ONE = "one"
+            TWO = "two"
+
+        class Stuff(object):
+            def __init__(self, machine_cls):
+                self.state = None
+                self.machine = machine_cls(states=States, initial=States.ONE, model=self)
+                self.machine.add_transition("advance", States.ONE, States.TWO)
+
+        s = Stuff(self.machine_cls)
+        assert s.is_ONE()
+        s.advance()
+        assert s.is_TWO()
+
 
 @skipIf(enum is None, "enum is not available")
 class TestNestedStateEnums(TestEnumsAsStates):
diff --git a/tests/test_markup.py b/tests/test_markup.py
index 80d50dee..aa03c7e6 100644
--- a/tests/test_markup.py
+++ b/tests/test_markup.py
@@ -3,13 +3,18 @@
 except ImportError:
     pass
 
+try:
+    import enum
+except ImportError:
+    enum = None
+
 from transitions.extensions.markup import MarkupMachine, rep
 from transitions.extensions.factory import HierarchicalMarkupMachine
 from .utils import Stuff
 from functools import partial
 
 
-from unittest import TestCase
+from unittest import TestCase, skipIf
 
 try:
     from unittest.mock import MagicMock
@@ -158,3 +163,23 @@ def setUp(self):
         self.machine_cls = HierarchicalMarkupMachine
         self.num_trans = len(self.transitions)
         self.num_auto = self.num_trans + 9**2
+
+
+@skipIf(enum is None, "enum is not available")
+class TestMarkupMachineEnum(TestMarkupMachine):
+    class States(enum.Enum):
+        A = 1
+        B = 2
+        C = 3
+        D = 4
+
+    def setUp(self):
+        self.machine_cls = MarkupMachine
+        self.states = TestMarkupMachineEnum.States
+        self.transitions = [
+            {'trigger': 'walk', 'source': self.states.A, 'dest': self.states.B},
+            {'trigger': 'run', 'source': self.states.B, 'dest': self.states.C},
+            {'trigger': 'sprint', 'source': self.states.C, 'dest': self.states.D}
+        ]
+        self.num_trans = len(self.transitions)
+        self.num_auto = self.num_trans + len(self.states)**2
diff --git a/transitions/core.py b/transitions/core.py
index 0a44f764..15dad6f0 100644
--- a/transitions/core.py
+++ b/transitions/core.py
@@ -858,7 +858,7 @@ def add_transition(self, trigger, source, dest, conditions=None,
             for model in self.models:
                 self._add_trigger_to_model(trigger, model)
 
-        if isinstance(source, string_types):
+        if isinstance(source, string_types) and not isinstance(source, Enum):
             source = list(self.states.keys()) if source == self.wildcard_all else [source]
         else:
             source = [s.name if self._has_state(s) or isinstance(s, Enum) else s for s in listify(source)]
diff --git a/transitions/extensions/diagrams.py b/transitions/extensions/diagrams.py
index aad0fbc7..ab4cdd56 100644
--- a/transitions/extensions/diagrams.py
+++ b/transitions/extensions/diagrams.py
@@ -3,6 +3,7 @@
 
 import warnings
 import logging
+from enum import Enum
 from functools import partial
 
 _LOGGER = logging.getLogger(__name__)
@@ -164,7 +165,10 @@ def _get_graph(self, model, title=None, force_new=False, show_roi=False):
             grph = self.graph_cls(self, title=title if title is not None else self.title)
             self.model_graphs[model] = grph
             try:
-                self.model_graphs[model].set_node_style(model.state, 'active')
+                if isinstance(model.state, Enum):
+                    self.model_graphs[model].set_node_style(model.state.name, 'active')
+                else:
+                    self.model_graphs[model].set_node_style(model.state, 'active')
             except AttributeError:
                 _LOGGER.info("Could not set active state of diagram")
         try:
diff --git a/transitions/extensions/markup.py b/transitions/extensions/markup.py
index de1e0c88..e3d113d1 100644
--- a/transitions/extensions/markup.py
+++ b/transitions/extensions/markup.py
@@ -2,6 +2,7 @@
 from functools import partial
 import itertools
 import importlib
+from enum import Enum
 from collections import defaultdict
 
 from ..core import Machine
@@ -67,7 +68,10 @@ def _convert_states(self, states):
         markup_states = []
         for state in states:
             s_def = _convert(state, self.state_attributes, self.skip_references)
-            s_def['name'] = getattr(state, '_name', state.name)
+            if isinstance(state, Enum):
+                s_def['name'] = state.name
+            else:
+                s_def['name'] = getattr(state, '_name', state.name)
             if getattr(state, 'children', False):
                 s_def['children'] = self._convert_states(state.children)
             markup_states.append(s_def)
@@ -153,7 +157,9 @@ def _convert(obj, attributes, skip):
         val = getattr(obj, key, False)
         if not val:
             continue
-        if isinstance(val, string_types):
+        if isinstance(val, Enum):
+            s[key] = val.name
+        elif isinstance(val, string_types):
             s[key] = val
         else:
             try: