diff --git a/openmc/config.py b/openmc/config.py
index 65b7e08639..23a3554679 100644
--- a/openmc/config.py
+++ b/openmc/config.py
@@ -4,6 +4,8 @@ from pathlib import Path
 
 from openmc.data import DataLibrary
 
+__all__ = ["config"]
+
 
 class _Config(MutableMapping):
     def __init__(self, data=()):
@@ -39,23 +41,29 @@ class _Config(MutableMapping):
         return repr(self._mapping)
 
 
-# Create default configuration
-config = _Config()
+def _default_config():
+    """Return default configuration"""
+    config = _Config()
 
-# Set cross sections using environment variable
-if "OPENMC_CROSS_SECTIONS" in os.environ:
-    config['cross_sections'] = os.environ["OPENMC_CROSS_SECTIONS"]
-if "OPENMC_MG_CROSS_SECTIONS" in os.environ:
-    config['mg_cross_sections'] = os.environ["OPENMC_MG_CROSS_SECTIONS"]
+    # Set cross sections using environment variable
+    if "OPENMC_CROSS_SECTIONS" in os.environ:
+        config['cross_sections'] = os.environ["OPENMC_CROSS_SECTIONS"]
+    if "OPENMC_MG_CROSS_SECTIONS" in os.environ:
+        config['mg_cross_sections'] = os.environ["OPENMC_MG_CROSS_SECTIONS"]
 
-# Check for depletion chain in cross_sections.xml
-# Set depletion chain
-chain_file = os.environ.get("OPENMC_DEPLETE_CHAIN")
-if chain_file is None and config['cross_sections'] is not None:
-    data = DataLibrary.from_xml(config['cross_sections'])
-    for lib in reversed(data.libraries):
-        if lib['type'] == 'depletion_chain':
-            chain_file = lib['path']
-            break
-if chain_file is not None:
-    config['chain_file'] = chain_file
+    # Check for depletion chain in cross_sections.xml
+    # Set depletion chain
+    chain_file = os.environ.get("OPENMC_DEPLETE_CHAIN")
+    if chain_file is None and config['cross_sections'] is not None:
+        data = DataLibrary.from_xml(config['cross_sections'])
+        for lib in reversed(data.libraries):
+            if lib['type'] == 'depletion_chain':
+                chain_file = lib['path']
+                break
+    if chain_file is not None:
+        config['chain_file'] = chain_file
+
+    return config
+
+
+config = _default_config()