diff --git a/tests/IL2C.Core.Test.RuntimeSystems/TypeRelations/TypeImplements.cs b/tests/IL2C.Core.Test.RuntimeSystems/TypeRelations/TypeImplements.cs
index fcba003d..8a86a8f3 100644
--- a/tests/IL2C.Core.Test.RuntimeSystems/TypeRelations/TypeImplements.cs
+++ b/tests/IL2C.Core.Test.RuntimeSystems/TypeRelations/TypeImplements.cs
@@ -262,6 +262,7 @@ public class InstanceMultipleImplement3DepthType : InstanceMultipleImplement2Dep
     [TestId("TypeRelations")]
     [TestCase("223", "InstanceImplement", 123, IncludeTypes = new[] { typeof(InstanceImplementType), typeof(IInterfaceType1) })]
     [TestCase("223", "InstanceImplementFromInterface", 123, IncludeTypes = new[] { typeof(InstanceImplementType), typeof(IInterfaceType1) })]
+    [TestCase("223", "InstanceImplementFromInterfaceByClass", 123, IncludeTypes = new[] { typeof(InstanceImplementType), typeof(IInterfaceType1) })]
     [TestCase("223", "InstanceImplementExplicitlyTypeFromInterface", 123, IncludeTypes = new[] { typeof(InstanceImplementExplicitlyType), typeof(IInterfaceType1) })]
     [TestCase("223", "InstanceImplementExplicitlyTypeFromInterfaceByClass", 123, IncludeTypes = new[] { typeof(InstanceImplementExplicitlyType), typeof(IInterfaceType1) })]
     [TestCase("223", "InstanceMultipleImplement1", 123, IncludeTypes = new[] { typeof(InstanceMultipleImplementType), typeof(IInterfaceType1), typeof(IInterfaceType2) })]
@@ -307,6 +308,9 @@ public static string InstanceImplementFromInterface(int value)
             return inst.GetStringFromInt32(value);
         }
 
+        [MethodImpl(MethodImplOptions.ForwardRef)]
+        public static extern string InstanceImplementFromInterfaceByClass(int value);
+
         public static string InstanceImplementExplicitlyTypeFromInterface(int value)
         {
             IInterfaceType1 inst = new InstanceImplementExplicitlyType();
diff --git a/tests/IL2C.Core.Test.RuntimeSystems/TypeRelations/TypeImplements.il b/tests/IL2C.Core.Test.RuntimeSystems/TypeRelations/TypeImplements.il
index 97ce07e8..1be08a3a 100644
--- a/tests/IL2C.Core.Test.RuntimeSystems/TypeRelations/TypeImplements.il
+++ b/tests/IL2C.Core.Test.RuntimeSystems/TypeRelations/TypeImplements.il
@@ -1,5 +1,13 @@
 .class public IL2C.RuntimeSystems.TypeImplements
 {
+    .method public static string InstanceImplementFromInterfaceByClass(int32 v) cil managed
+    {
+        .maxstack 2
+        newobj instance void IL2C.RuntimeSystems.InstanceImplementType::.ctor()
+        ldarg.0
+        callvirt instance string IL2C.RuntimeSystems.IInterfaceType1::GetStringFromInt32(int32)
+        ret
+    }
     .method public static string InstanceImplementExplicitlyTypeFromInterfaceByClass(int32 v) cil managed
     {
         .maxstack 2