diff --git a/app/models/assay.rb b/app/models/assay.rb
index a1cec65479..c5095524a9 100644
--- a/app/models/assay.rb
+++ b/app/models/assay.rb
@@ -305,11 +305,12 @@ def self.filter_by_projects(projects)
   private
 
   def study_matches_observation_units_if_present
+    return if samples.empty?
     samples.each do |sample|
-        if sample.observation_unit && sample.observation_unit.study != study
+      if sample.observation_unit && sample.observation_unit.study != study
           errors.add(:study, 'must match the associated observation unit')
           return false
-        end
+      end
     end
   end
 
diff --git a/app/models/observation_unit.rb b/app/models/observation_unit.rb
index 755fbac4f5..182e3c5f2f 100644
--- a/app/models/observation_unit.rb
+++ b/app/models/observation_unit.rb
@@ -53,6 +53,7 @@ def related_publication_ids
   private
 
   def study_matches_assays_if_present
+    return if samples.empty?
     samples.each do |sample|
       sample.assays.each do |assay|
         if assay.study != study