diff --git a/stix2/properties.py b/stix2/properties.py
index 0b52544..e62302a 100644
--- a/stix2/properties.py
+++ b/stix2/properties.py
@@ -75,7 +75,7 @@ class Property(object):
 
 class ListProperty(Property):
 
-    def __init__(self, contained):
+    def __init__(self, contained, **kwargs):
         """
         contained should be a type whose constructor creates an object from the value
         """
@@ -85,6 +85,7 @@ class ListProperty(Property):
             self.contained = bool
         else:
             self.contained = contained
+        super(ListProperty, self).__init__(**kwargs)
 
     def validate(self, value):
         try:
@@ -108,7 +109,6 @@ class ListProperty(Property):
         return list_
 
     def clean(self, value):
-        return [self.contained(x) for x in value]
         try:
             return [self.contained(x) for x in value]
         except TypeError:
@@ -117,12 +117,12 @@ class ListProperty(Property):
 
 class StringProperty(Property):
 
-    def __init__(self):
+    def __init__(self, **kwargs):
         if sys.version_info[0] == 2:
             self.string_type = unicode
         else:
             self.string_type = str
-        super(StringProperty, self).__init__()
+        super(StringProperty, self).__init__(**kwargs)
 
     def clean(self, value):
         return self.string_type(value)
diff --git a/stix2/sdo.py b/stix2/sdo.py
index ffe073d..8a45ff4 100644
--- a/stix2/sdo.py
+++ b/stix2/sdo.py
@@ -2,7 +2,8 @@
 
 from .base import _STIXBase
 from .common import COMMON_PROPERTIES
-from .properties import IDProperty, TypeProperty, Property
+from .properties import (StringProperty, IDProperty, ListProperty,
+                         TypeProperty, Property)
 from .utils import NOW
 
 
@@ -105,9 +106,9 @@ class Malware(_STIXBase):
     _properties.update({
         'type': TypeProperty(_type),
         'id': IDProperty(_type),
-        'labels': Property(required=True),
-        'name': Property(required=True),
-        'description': Property(),
+        'labels': ListProperty(StringProperty, required=True),
+        'name': StringProperty(required=True),
+        'description': StringProperty(),
         'kill_chain_phases': Property(),
     })
 
diff --git a/stix2/test/test_malware.py b/stix2/test/test_malware.py
index 8e628ab..7668ffa 100644
--- a/stix2/test/test_malware.py
+++ b/stix2/test/test_malware.py
@@ -2,6 +2,7 @@ import datetime as dt
 
 import pytest
 import pytz
+import re
 
 import stix2
 
@@ -99,3 +100,10 @@ def test_parse_malware():
     assert mal.modified == "2016-05-12T08:17:27Z"
     assert mal.labels == ['ransomware']
     assert mal.name == "Cryptolocker"
+
+
+def test_parse_malware_invalid_labels():
+    data = re.compile('\[.+\]', re.DOTALL).sub('1', EXPECTED_MALWARE)
+    with pytest.raises(ValueError) as excinfo:
+        stix2.parse(data)
+    assert "Invalid value for Malware 'labels'" in str(excinfo.value)