diff --git a/src/citrine/__init__.py b/src/citrine/__init__.py
index effc6d496..db9278ded 100644
--- a/src/citrine/__init__.py
+++ b/src/citrine/__init__.py
@@ -5,5 +5,12 @@
 https://citrineinformatics.github.io/citrine-python/index.html
 
 """
+import warnings
+
 from citrine.citrine import Citrine  # noqa: F401
 from .__version__ import __version__  # noqa: F401
+
+# Python's default warning filter hides DeprecationWarning unless triggered from
+# __main__ (PEP 565). Surface DeprecationWarnings raised from citrine.* so users
+# see them before the deprecated APIs are removed.
+warnings.filterwarnings("default", category=DeprecationWarning, module=r"citrine(\.|$)")
diff --git a/src/citrine/__version__.py b/src/citrine/__version__.py
index c7a18d13e..4b56dfc53 100644
--- a/src/citrine/__version__.py
+++ b/src/citrine/__version__.py
@@ -1 +1 @@
-__version__ = "4.0.3"
+__version__ = "4.0.4"
diff --git a/tests/test_citrine.py b/tests/test_citrine.py
index 1b24c9221..42dccb8f1 100644
--- a/tests/test_citrine.py
+++ b/tests/test_citrine.py
@@ -1,4 +1,5 @@
 import platform
+import warnings
 from datetime import datetime, timezone
 
 import jwt
@@ -6,6 +7,7 @@
 import requests_mock
 
 from citrine import Citrine
+from citrine._utils.functions import migrate_deprecated_argument
 
 
 def refresh_token(expiration: datetime = None) -> dict:
@@ -103,3 +105,20 @@ def test_citrine_user_agent():
             # enforce them to be ints.  It's common to see strings used
             # as the patch version
             assert len(product_version.split('.')) == 3
+
+
+def test_citrine_deprecation_warnings_visible_by_default():
+    import importlib
+
+    import citrine
+
+    with warnings.catch_warnings(record=True) as caught:
+        warnings.resetwarnings()
+        # Mirror Python's default filter: DeprecationWarning hidden outside __main__.
+        warnings.simplefilter("ignore", category=DeprecationWarning)
+        importlib.reload(citrine)
+
+        migrate_deprecated_argument(None, "new", "value", "old")
+
+    deprecations = [w for w in caught if issubclass(w.category, DeprecationWarning)]
+    assert any("'old' is deprecated" in str(w.message) for w in deprecations)