diff --git a/tests.cfg b/tests.cfg
index 05c552f9de..9cb9373fb4 100644
--- a/tests.cfg
+++ b/tests.cfg
@@ -126,6 +126,15 @@ recipe = collective.xmltestreport
 eggs = ${buildout:test-eggs}
 defaults = ['--auto-color', '--auto-progress', '--ignore_dir=.git', '--ignore_dir=bower_components', '--ignore_dir=node_modules']
 environment = environment
+initialization =
+# Ensures that tests using datetime will work locally on machines using TZ = GMT
+    os.environ['TZ'] = 'UTC'
+    import time
+    try:
+        time.tzset()
+    except AttributeError:
+        # function not available on Windows
+        pass
 
 [robot]
 recipe = zc.recipe.egg