diff --git a/app/models/ultima_sequencing_request.rb b/app/models/ultima_sequencing_request.rb
index 63be2fae7b..00c5cdb18a 100644
--- a/app/models/ultima_sequencing_request.rb
+++ b/app/models/ultima_sequencing_request.rb
@@ -35,6 +35,8 @@ class UltimaSequencingRequest < SequencingRequest
   # id_pool_lims, and request_order.
   # @return [String] unique wafer ID for LIMS
   def id_wafer_lims
+    return nil unless batch && source_labware && position
+
     "#{batch.id}_#{source_labware.human_barcode}_#{position}"
   end
 end
diff --git a/app/resources/api/v2/request_resource.rb b/app/resources/api/v2/request_resource.rb
index 9cfb7f8a55..a37976c0c6 100644
--- a/app/resources/api/v2/request_resource.rb
+++ b/app/resources/api/v2/request_resource.rb
@@ -115,6 +115,8 @@ class RequestResource < BaseResource
       #   @note This attribute is read-only.
       attribute :library_type, readonly: true
 
+      attribute :id_wafer_lims, readonly: true
+
       ###
       # Relationships
       ###
@@ -204,6 +206,10 @@ def pre_capture_pool_id
       def library_type
         _model.try(:library_type)
       end
+
+      def id_wafer_lims
+        _model.try(:id_wafer_lims)
+      end
     end
   end
 end