diff --git a/tests/__init__.py b/tests/__init__.py
index b99a563a..ab756bf7 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -38,6 +38,11 @@ class TestBase(unittest.TestCase):
         init_i18n()
 
 
+@lru_cache(1)
+def running_in_ci():
+    return "CI" in os.environ
+
+
 def run(cmd, verbosity=0, **kwargs):
     """Run command without error checking.
     @return: command return code"""
diff --git a/tests/checker/test_httpbin.py b/tests/checker/test_httpbin.py
index db17f6c9..6c4d6128 100644
--- a/tests/checker/test_httpbin.py
+++ b/tests/checker/test_httpbin.py
@@ -16,15 +16,14 @@
 """
 Test http stuff with httpbin.org.
 """
-import os
 import re
-from tests import need_network
+from tests import need_network, running_in_ci
 from . import LinkCheckTest
 
 
 def get_httpbin_url(path):
     """Get httpbin URL."""
-    if "CI" in os.environ:
+    if running_in_ci():
         host = "localhost:8080"
     else:
         host = "httpbin.org"