diff --git a/instrumentation/opentelemetry-instrumentation-flask/src/opentelemetry/instrumentation/flask/__init__.py b/instrumentation/opentelemetry-instrumentation-flask/src/opentelemetry/instrumentation/flask/__init__.py
index 9691f884ab..0d36763e7d 100644
--- a/instrumentation/opentelemetry-instrumentation-flask/src/opentelemetry/instrumentation/flask/__init__.py
+++ b/instrumentation/opentelemetry-instrumentation-flask/src/opentelemetry/instrumentation/flask/__init__.py
@@ -536,6 +536,7 @@ def _teardown_request(exc):
 
         if flask.request.environ.get(_ENVIRON_TOKEN, None):
             context.detach(flask.request.environ.get(_ENVIRON_TOKEN))
+            flask.request.environ[_ENVIRON_TOKEN] = None
 
     return _teardown_request