diff --git a/tox.ini b/tox.ini
index 44425ae4..7677ed27 100644
--- a/tox.ini
+++ b/tox.ini
@@ -98,9 +98,6 @@ passenv =
     ANSIBLE_*
     HOME
     MITOGEN_*
-    # Azure DevOps, TF_BUILD is set to 'True' when running in a build task
-    # https://learn.microsoft.com/en-us/azure/devops/pipelines/build/variables
-    TF_BUILD
 setenv =
     # See also azure-pipelines.yml
     ANSIBLE_STRATEGY = mitogen_linear