diff --git a/stix2/test/v21/test_bundle.py b/stix2/test/v21/test_bundle.py
index 9b78215..a884b1f 100644
--- a/stix2/test/v21/test_bundle.py
+++ b/stix2/test/v21/test_bundle.py
@@ -32,7 +32,7 @@ EXPECTED_BUNDLE = """{
             "malware_types": [
                 "ransomware"
             ],
-            "is_family": False
+            "is_family": "False"
         },
         {
             "type": "relationship",
diff --git a/stix2/test/v21/test_environment.py b/stix2/test/v21/test_environment.py
index 53ab744..6887e41 100644
--- a/stix2/test/v21/test_environment.py
+++ b/stix2/test/v21/test_environment.py
@@ -220,7 +220,7 @@ def test_parse_malware():
         "malware_types": [
             "ransomware"
         ],
-        "is_family": False
+        "is_family": "False"
     }"""
     mal = env.parse(data, version="2.1")
 
diff --git a/stix2/test/v21/test_indicator.py b/stix2/test/v21/test_indicator.py
index d061104..b68b887 100644
--- a/stix2/test/v21/test_indicator.py
+++ b/stix2/test/v21/test_indicator.py
@@ -99,7 +99,7 @@ def test_indicator_required_properties():
 
     assert excinfo.value.cls == stix2.v21.Indicator
     assert excinfo.value.properties == ["indicator_types", "pattern", "valid_from"]
-    assert str(excinfo.value) == "No values for required properties for Indicator: (indicator_types, pattern)."
+    assert str(excinfo.value) == "No values for required properties for Indicator: (indicator_types, pattern, valid_from)."
 
 
 def test_indicator_required_property_pattern():
@@ -194,6 +194,7 @@ def test_invalid_indicator_pattern():
         stix2.v21.Indicator(
             indicator_types=['malicious-activity'],
             pattern='[file:hashes.MD5 = "d41d8cd98f00b204e9800998ecf8427e"]',
+            valid_from="2017-01-01T12:34:56Z",
         )
     assert excinfo.value.cls == stix2.v21.Indicator
     assert excinfo.value.prop_name == 'pattern'
diff --git a/stix2/test/v21/test_malware.py b/stix2/test/v21/test_malware.py
index e6dfc2e..bf5b538 100644
--- a/stix2/test/v21/test_malware.py
+++ b/stix2/test/v21/test_malware.py
@@ -18,7 +18,7 @@ EXPECTED_MALWARE = """{
     "malware_types": [
         "ransomware"
     ],
-    "is_family": False
+    "is_family": "False"
 }"""