diff --git a/app/models/concerns/has_custom_fields.rb b/app/models/concerns/has_custom_fields.rb
index 25a6422b0e..c6e929d8e0 100644
--- a/app/models/concerns/has_custom_fields.rb
+++ b/app/models/concerns/has_custom_fields.rb
@@ -161,7 +161,7 @@ module HasCustomFields
 
       array_fields = {}
 
-      _custom_fields.each do |f|
+      _custom_fields.reload.each do |f|
         if dup[f.name].is_a? Array
           # we need to collect Arrays fully before we can compare them
           if !array_fields.has_key?(f.name)
@@ -171,7 +171,7 @@ module HasCustomFields
           end
         elsif dup[f.name].is_a? Hash
           if dup[f.name].to_json != f.value
-            f.destroy
+            f.destroy!
           else
             dup.delete(f.name)
           end
@@ -180,7 +180,7 @@ module HasCustomFields
           self.class.append_custom_field(t, f.name, f.value)
 
           if dup[f.name] != t[f.name]
-            f.destroy
+            f.destroy!
           else
             dup.delete(f.name)
           end
@@ -198,11 +198,12 @@ module HasCustomFields
 
       dup.each do |k, v|
         if v.is_a? Array
-          v.each { |subv| _custom_fields.create(name: k, value: subv) }
-        elsif v.is_a? Hash
-          _custom_fields.create(name: k, value: v.to_json)
+          v.each { |subv| _custom_fields.create!(name: k, value: subv) }
         else
-          _custom_fields.create(name: k, value: v)
+          _custom_fields.create!(
+            name: k,
+            value: v.is_a?(Hash) ? v.to_json : v
+          )
         end
       end
 
diff --git a/spec/components/concern/has_custom_fields_spec.rb b/spec/components/concern/has_custom_fields_spec.rb
index fc1f1a43e8..f1bf5933cb 100644
--- a/spec/components/concern/has_custom_fields_spec.rb
+++ b/spec/components/concern/has_custom_fields_spec.rb
@@ -193,5 +193,27 @@ describe HasCustomFields do
       expect(fields[item1.id]['not_whitelisted']).to be_blank
       expect(fields[item2.id]['e']).to eq('hallo')
     end
+
+    it "handles interleaving saving properly" do
+      field_type = 'deep-nest-test'
+      CustomFieldsTestItem.register_custom_field_type(field_type, :json)
+      test_item = CustomFieldsTestItem.create!
+
+      test_item.custom_fields[field_type] ||= {}
+      test_item.custom_fields[field_type]['b'] ||= {}
+      test_item.custom_fields[field_type]['b']['c'] = 'd'
+      test_item.save_custom_fields(true)
+
+      db_item = CustomFieldsTestItem.find(test_item.id)
+      db_item.custom_fields[field_type]['b']['e'] = 'f'
+      test_item.custom_fields[field_type]['b']['e'] = 'f'
+      expected = { field_type => { 'b' => { 'c' => 'd', 'e' => 'f' } } }
+
+      db_item.save_custom_fields(true)
+      expect(db_item.reload.custom_fields).to eq(expected)
+
+      test_item.save_custom_fields(true)
+      expect(test_item.reload.custom_fields).to eq(expected)
+    end
   end
 end