diff --git a/pw_software_update/bundled_update_service.cc b/pw_software_update/bundled_update_service.cc
index 9cc4558..b424fab 100644
--- a/pw_software_update/bundled_update_service.cc
+++ b/pw_software_update/bundled_update_service.cc
@@ -132,11 +132,11 @@
 
 Status BundledUpdateService::SetTransferred(const pw_protobuf_Empty&,
                                             BundledUpdateStatus& response) {
-  std::lock_guard lock(mutex_);
   const BundledUpdateState state = status_.acquire()->state;
 
   if (state != pw_software_update_BundledUpdateState_Enum_TRANSFERRING &&
       state != pw_software_update_BundledUpdateState_Enum_INACTIVE) {
+    std::lock_guard lock(mutex_);
     SET_ERROR(pw_software_update_BundledUpdateResult_Enum_UNKNOWN_ERROR,
               "SetTransferred() can only be called from TRANSFERRING or "
               "INACTIVE state. State: %d",