diff --git a/openmc/capi/__init__.py b/openmc/capi/__init__.py
index d302001c99..bc173f9946 100644
--- a/openmc/capi/__init__.py
+++ b/openmc/capi/__init__.py
@@ -15,7 +15,6 @@ objects in the :mod:`openmc.capi` subpackage, for example:
 from ctypes import CDLL
 import os
 import sys
-from warnings import warn
 
 import pkg_resources
 
@@ -36,10 +35,7 @@ else:
     # available. Instead, we create a mock object so that when the modules
     # within the openmc.capi package try to configure arguments and return
     # values for symbols, no errors occur
-    try:
-        from unittest.mock import Mock
-    except ImportError:
-        from mock import Mock
+    from unittest.mock import Mock
     _dll = Mock()
 
 from .error import *
@@ -50,6 +46,3 @@ from .cell import *
 from .filter import *
 from .tally import *
 from .settings import settings
-
-warn("The Python bindings to OpenMC's C API are still unstable "
-     "and may change substantially in future releases.", FutureWarning)