diff --git a/tools/run_tests/run_tests.py b/tools/run_tests/run_tests.py
index cc004f38d7f1852a578515d45bd260d7317d6d78..2df82adf0a7ed54a99ec3939d3ff371584848b0a 100755
--- a/tools/run_tests/run_tests.py
+++ b/tools/run_tests/run_tests.py
@@ -360,7 +360,7 @@ class PythonLanguage(object):
           ['tools/run_tests/run_python.sh'],
           None,
           environ=dict(environment.items() +
-                       [('GPRC_PYTHON_TESTRUNNER_FILTER', suite_name)]),
+                       [('GRPC_PYTHON_TESTRUNNER_FILTER', suite_name)]),
           shortname='py.test.%s' % suite_name,
           timeout_seconds=5*60)
           for suite_name in tests_json]