diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index f9b2fff..0a221d1 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -3371,7 +3371,7 @@
         psa_sign_hash_abort_internal(operation);
     }
 
-    unlock_status = psa_unregister_read(slot);
+    unlock_status = psa_unregister_read_under_mutex(slot);
 
     if (unlock_status != PSA_SUCCESS) {
         operation->error_occurred = 1;