diff --git a/.release-version b/.release-version
index 4a788a01d..c3f6bdc3d 100644
--- a/.release-version
+++ b/.release-version
@@ -1 +1 @@
-3.6.3
+3.6.4
\ No newline at end of file
diff --git a/app/models/pacbio/well_library.rb b/app/models/pacbio/well_library.rb
index 1be7d4f2e..ad4588092 100644
--- a/app/models/pacbio/well_library.rb
+++ b/app/models/pacbio/well_library.rb
@@ -10,6 +10,6 @@ class WellLibrary < ApplicationRecord
     belongs_to :library, class_name: 'Pacbio::Library', foreign_key: :pacbio_library_id,
                          inverse_of: :well_libraries
 
-    delegate :barcode, to: :library
+    delegate :barcode, to: :library, allow_nil: true
   end
 end
diff --git a/spec/models/pacbio/well_library_spec.rb b/spec/models/pacbio/well_library_spec.rb
index 12c6cd09f..f076325a8 100644
--- a/spec/models/pacbio/well_library_spec.rb
+++ b/spec/models/pacbio/well_library_spec.rb
@@ -17,4 +17,10 @@
     expect(well_library.barcode).to be_present
   end
 
+  it 'if the well is nil the barcode will be nil' do
+    well_library = build(:pacbio_well_library, library: nil)
+    expect(well_library.barcode).to be_nil
+
+  end
+
 end