diff --git a/app/models/concerns/has_custom_fields.rb b/app/models/concerns/has_custom_fields.rb
index a98aad45b3f..923efe846db 100644
--- a/app/models/concerns/has_custom_fields.rb
+++ b/app/models/concerns/has_custom_fields.rb
@@ -193,7 +193,7 @@ module HasCustomFields
       if row_count == 0
         _custom_fields.create!(name: k, value: v)
       end
-      custom_fields[k] = v
+      custom_fields[k.to_s] = v # We normalize custom_fields as strings
     end
   end
 
diff --git a/spec/components/concern/has_custom_fields_spec.rb b/spec/components/concern/has_custom_fields_spec.rb
index 5696f113f12..24ecefaca54 100644
--- a/spec/components/concern/has_custom_fields_spec.rb
+++ b/spec/components/concern/has_custom_fields_spec.rb
@@ -313,6 +313,30 @@ describe HasCustomFields do
         expect(test_item.custom_fields['hello']).to eq('world')
         expect(test_item.custom_fields['abc']).to eq('ghi')
       end
+
+      it 'allows upsert to use keywords' do
+        test_item = CustomFieldsTestItem.create
+        test_item.upsert_custom_fields(hello: 'world', abc: 'def')
+
+        # In memory
+        expect(test_item.custom_fields['hello']).to eq('world')
+        expect(test_item.custom_fields['abc']).to eq('def')
+
+        # Persisted
+        test_item.reload
+        expect(test_item.custom_fields['hello']).to eq('world')
+        expect(test_item.custom_fields['abc']).to eq('def')
+
+        # In memory
+        test_item.upsert_custom_fields('abc' => 'ghi')
+        expect(test_item.custom_fields['hello']).to eq('world')
+        expect(test_item.custom_fields['abc']).to eq('ghi')
+
+        # Persisted
+        test_item.reload
+        expect(test_item.custom_fields['hello']).to eq('world')
+        expect(test_item.custom_fields['abc']).to eq('ghi')
+      end
     end
   end
 end