diff --git a/proto/marshal/collections/repeated.py b/proto/marshal/collections/repeated.py
index 30fa68d0..01b5d2fd 100644
--- a/proto/marshal/collections/repeated.py
+++ b/proto/marshal/collections/repeated.py
@@ -174,5 +174,5 @@ def __setitem__(self, key, value):
 
     def insert(self, index: int, value):
         """Insert ``value`` in the sequence before ``index``."""
-        pb_value = self._marshal.to_proto(self._pb_type, value, strict=True)
+        pb_value = self._marshal.to_proto(self._pb_type, value)
         self.pb.insert(index, pb_value)
diff --git a/tests/test_marshal_strict.py b/tests/test_marshal_strict.py
new file mode 100644
index 00000000..75e2f05d
--- /dev/null
+++ b/tests/test_marshal_strict.py
@@ -0,0 +1,24 @@
+# Copyright (C) 2021  Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import proto
+from proto.marshal.marshal import BaseMarshal
+import pytest
+
+
+def test_strict_to_proto():
+    m = BaseMarshal()
+
+    with pytest.raises(TypeError):
+        m.to_proto(dict, None, strict=True)
diff --git a/tests/test_marshal_types_enum.py b/tests/test_marshal_types_enum.py
index 1d302053..6cd348c3 100644
--- a/tests/test_marshal_types_enum.py
+++ b/tests/test_marshal_types_enum.py
@@ -58,3 +58,35 @@ class Foo(proto.Enum):
     with mock.patch.object(warnings, "warn") as warn:
         assert enum_rule.to_python(4) == 4
         warn.assert_called_once_with("Unrecognized Foo enum value: 4")
+
+
+def test_enum_append():
+    class Bivalve(proto.Enum):
+        CLAM = 0
+        OYSTER = 1
+
+    class MolluscContainer(proto.Message):
+        bivalves = proto.RepeatedField(proto.ENUM, number=1, enum=Bivalve,)
+
+    mc = MolluscContainer()
+    clam = Bivalve.CLAM
+    mc.bivalves.append(clam)
+    mc.bivalves.append(1)
+
+    assert mc.bivalves == [clam, Bivalve.OYSTER]
+
+
+def test_enum_map_insert():
+    class Bivalve(proto.Enum):
+        CLAM = 0
+        OYSTER = 1
+
+    class MolluscContainer(proto.Message):
+        bivalves = proto.MapField(proto.STRING, proto.ENUM, number=1, enum=Bivalve,)
+
+    mc = MolluscContainer()
+    clam = Bivalve.CLAM
+    mc.bivalves["clam"] = clam
+    mc.bivalves["oyster"] = 1
+
+    assert mc.bivalves == {"clam": clam, "oyster": Bivalve.OYSTER}