diff --git a/tests/test_dependencies.py b/tests/test_dependencies.py
index 4e4f190ab..93e7311d2 100644
--- a/tests/test_dependencies.py
+++ b/tests/test_dependencies.py
@@ -26,7 +26,7 @@ class ScrapyUtilsTest(unittest.TestCase):
 
         See https://github.com/scrapy/scrapy/pull/4814#issuecomment-706230011
         """
-        if not os.environ.get('SCRAPY_PINNED', None):
+        if not os.environ.get('_SCRAPY_PINNED', None):
             self.skipTest('Not in a pinned environment')
 
         tox_config_file_path = os.path.join(
diff --git a/tox.ini b/tox.ini
index ea71a2476..66866301c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -93,7 +93,7 @@ install_command =
     # Twisted gets installed.
     pip install --use-feature=2020-resolver {opts} {packages}
 setenv =
-    SCRAPY_PINNED=true
+    _SCRAPY_PINNED=true
 
 [testenv:pinned]
 deps =