diff --git a/tftest.py b/tftest.py
index 5b0ffbc..e160f21 100644
--- a/tftest.py
+++ b/tftest.py
@@ -333,7 +333,8 @@ def __init__(self, tfdir, basedir=None, binary='terraform', env=None,
     self.binary = binary
     self.tfdir = self._abspath(tfdir)
     self._env = env or {}
-    self.env = os.environ.copy()
+    self.env = {key: value for key,
+                value in os.environ.items() if key != 'TF_LOG'}
     self.tg_run_all = False
     self._plan_formatter = lambda out: TerraformPlanOutput(json.loads(out))
     self._output_formatter = lambda out: TerraformValueDict(