diff --git a/Assets/Scripts/RuntimeUnitTestToolkit/UnitTestRunner.cs b/Assets/Scripts/RuntimeUnitTestToolkit/UnitTestRunner.cs
index cbe63860..aad8cd15 100644
--- a/Assets/Scripts/RuntimeUnitTestToolkit/UnitTestRunner.cs
+++ b/Assets/Scripts/RuntimeUnitTestToolkit/UnitTestRunner.cs
@@ -5,7 +5,9 @@
 using UnityEngine.Events;
 using UnityEngine.UI;
 using System.Collections;
+#if CSHARP_7_OR_LATER
 using UniRx.Async;
+#endif
 
 namespace RuntimeUnitTestToolkit
 {
diff --git a/Assets/Scripts/Tests/Imported/TestImporter.cs b/Assets/Scripts/Tests/Imported/TestImporter.cs
index d7bd7f03..bc4e6a2e 100644
--- a/Assets/Scripts/Tests/Imported/TestImporter.cs
+++ b/Assets/Scripts/Tests/Imported/TestImporter.cs
@@ -17,6 +17,7 @@ namespace RuntimeUnitTestToolkit
 {
     public static class ImportUnitTestLoader
     {
+#if !(UNITY_4_5 || UNITY_4_6 || UNITY_4_7 || UNITY_5_0 || UNITY_5_1 || UNITY_5_2)
         [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.BeforeSceneLoad)]
         public static void Register()
         {
@@ -46,6 +47,7 @@ public static void Register()
             UnitTest.RegisterAllMethods<ToTest>();
             UnitTest.RegisterAllMethods<WhenAllTest>();
         }
+#endif
     }