diff --git a/app/services/api/v1/issues/create_service.rb b/app/services/api/v1/issues/create_service.rb
index 2069b876..ddb3b7af 100644
--- a/app/services/api/v1/issues/create_service.rb
+++ b/app/services/api/v1/issues/create_service.rb
@@ -11,7 +11,7 @@ class Api::V1::Issues::CreateService < ApplicationService
   validates :subject, presence: true
   validates :status_id, :priority_id, presence: true
   validates :project, :current_user, presence: true
-  validates :blockchain_token_num, numericality: {greater_than: 0}
+  validates :blockchain_token_num, numericality: {greater_than: 0}, allow_blank: true
 
   def initialize(project, params, current_user = nil)
     @project = project 
diff --git a/app/services/api/v1/issues/update_service.rb b/app/services/api/v1/issues/update_service.rb
index 4d349502..ddbd67d8 100644
--- a/app/services/api/v1/issues/update_service.rb
+++ b/app/services/api/v1/issues/update_service.rb
@@ -9,7 +9,7 @@ class Api::V1::Issues::UpdateService < ApplicationService
   attr_accessor :add_assigner_ids, :previous_issue_changes, :updated_issue, :atme_receivers
 
   validates :project, :issue, :current_user, presence: true
-  validates :blockchain_token_num, numericality: {greater_than: 0}
+  validates :blockchain_token_num, numericality: {greater_than: 0}, allow_blank: true
 
   def initialize(project, issue, params, current_user = nil) 
     @project = project