diff --git a/helpers/application_helper.rb b/helpers/application_helper.rb
index 04999f65..ad813e31 100644
--- a/helpers/application_helper.rb
+++ b/helpers/application_helper.rb
@@ -125,10 +125,10 @@ def reply(*response)
         check_access(obj) if LinkedData.settings.enable_security
 
         # Slice or set check
-        filter_for_slice(obj) if LinkedData.settings.enable_slices
+        obj = filter_for_slice(obj) if LinkedData.settings.enable_slices
 
         # Check for custom ontologies set by user
-        filter_for_user_onts(obj)
+        obj = filter_for_user_onts(obj)
 
         LinkedData::Serializer.build_response(@env, status: status, ld_object: obj)
       end
@@ -211,8 +211,8 @@ def restricted_ontologies(params=nil)
 
           found_onts = onts.length > 0
 
-          filter_for_slice(onts)
-          filter_for_user_onts(onts)
+          onts = filter_for_slice(onts)
+          onts = filter_for_user_onts(onts)
         end
         onts = filter_access(onts)
 
diff --git a/helpers/slices_helper.rb b/helpers/slices_helper.rb
index d17db53e..6f527f29 100644
--- a/helpers/slices_helper.rb
+++ b/helpers/slices_helper.rb
@@ -10,10 +10,8 @@ def filter_for_slice(obj)
 
         slice = current_slice()
 
-        if obj.is_a?(Enumerable)
-          if obj.first.is_a?(LinkedData::Models::Ontology)
-            obj.delete_if {|o| !slice.ontology_id_set.include?(o.id.to_s)}
-          end
+        if obj.is_a?(Enumerable) && obj.first.is_a?(LinkedData::Models::Ontology)
+          obj = obj.select { |o| slice.ontology_id_set.include?(o.id.to_s) }
         end
         obj
       end
@@ -35,4 +33,4 @@ def current_slice_acronyms
   end
 end
 
-helpers Sinatra::Helpers::SlicesHelper
\ No newline at end of file
+helpers Sinatra::Helpers::SlicesHelper
diff --git a/helpers/users_helper.rb b/helpers/users_helper.rb
index 5d4266c1..eeb6f800 100644
--- a/helpers/users_helper.rb
+++ b/helpers/users_helper.rb
@@ -12,7 +12,7 @@ def filter_for_user_onts(obj)
         user = env["REMOTE_USER"]
 
         if obj.first.is_a?(LinkedData::Models::Ontology)
-          obj.delete_if {|o| !user.custom_ontology_id_set.include?(o.id.to_s)}
+          obj = obj.select {|o| user.custom_ontology_id_set.include?(o.id.to_s)}
         end
 
         obj
@@ -21,4 +21,4 @@ def filter_for_user_onts(obj)
   end
 end
 
-helpers Sinatra::Helpers::UsersHelper
\ No newline at end of file
+helpers Sinatra::Helpers::UsersHelper