diff --git a/lib/fhir_models.rb b/lib/fhir_models.rb
index 61fa4a7b..53e59f10 100644
--- a/lib/fhir_models.rb
+++ b/lib/fhir_models.rb
@@ -1,4 +1,3 @@
 # require versions
 require_relative 'fhir_models/r4'
-require_relative 'fhir_models/r4b'
-require_relative 'fhir_models/r5'
+
diff --git a/test/unit/version_test.rb b/test/unit/version_test.rb
index e21b023c..d40ccb81 100644
--- a/test/unit/version_test.rb
+++ b/test/unit/version_test.rb
@@ -1,4 +1,5 @@
 require_relative '../test_helper'
+require_relative '../../lib/fhir_models/r4b'
 
 class VersionTest < Test::Unit::TestCase
   def test_json_version