diff --git a/src/cloudformation_cli_python_lib/boto3_proxy.py b/src/cloudformation_cli_python_lib/boto3_proxy.py
index 74ff100..95a1971 100644
--- a/src/cloudformation_cli_python_lib/boto3_proxy.py
+++ b/src/cloudformation_cli_python_lib/boto3_proxy.py
@@ -14,9 +14,9 @@ def __init__(self, session: Session):
 
 
 def _get_boto_session(
-    credentials: Optional[Credentials], region: Optional[str] = None
+    credentials: Optional[Credentials], region: Optional[str] = "us-east-1"
 ) -> Optional[SessionProxy]:
-    if not credentials:
+    if not credentials or not region:
         return None
     session = Session(
         aws_access_key_id=credentials.accessKeyId,
diff --git a/tests/lib/boto3_proxy_test.py b/tests/lib/boto3_proxy_test.py
index 4995d6e..7ff3bac 100644
--- a/tests/lib/boto3_proxy_test.py
+++ b/tests/lib/boto3_proxy_test.py
@@ -3,7 +3,12 @@
 from cloudformation_cli_python_lib.utils import Credentials
 
 
-def test_get_boto_session_returns_proxy():
+def test_get_boto_session_region_returns_proxy():
+    proxy = _get_boto_session(Credentials("", "", ""), region="test-region")
+    assert isinstance(proxy, SessionProxy)
+
+
+def test_get_boto_session_no_region_returns_proxy():
     proxy = _get_boto_session(Credentials("", "", ""))
     assert isinstance(proxy, SessionProxy)
 
@@ -13,6 +18,11 @@ def test_get_boto_session_returns_none():
     assert proxy is None
 
 
+def test_get_boto_no_session_no_region_returns_none():
+    proxy = _get_boto_session(None, None)
+    assert proxy is None
+
+
 def test_can_retrieve_boto_session():
     proxy = _get_boto_session(Credentials("", "", ""))
     session = proxy.session