diff --git a/drivers/hwtracing/stm/policy.c b/drivers/hwtracing/stm/policy.c
index 4b9e44b227d8..4f932a419752 100644
--- a/drivers/hwtracing/stm/policy.c
+++ b/drivers/hwtracing/stm/policy.c
@@ -345,7 +345,11 @@ void stp_policy_unbind(struct stp_policy *policy)
 	stm->policy = NULL;
 	policy->stm = NULL;
 
+	/*
+	 * Drop the reference on the protocol driver and lose the link.
+	 */
 	stm_put_protocol(stm->pdrv);
+	stm->pdrv = NULL;
 	stm_put_device(stm);
 }