diff --git a/src/vm/block.cs b/src/vm/block.cs
index 59f2bbda..69c3d745 100644
--- a/src/vm/block.cs
+++ b/src/vm/block.cs
@@ -16,11 +16,6 @@ public enum BlockType
   DOWHILE   = 10,
 }
 
-public interface IDeferSupport
-{
-  void RegisterDefer(DeferBlock cb);
-}
-
 public struct DeferBlock
 {
   public VM.Frame frm;
@@ -82,7 +77,7 @@ public override string ToString()
   }
 }
 
-public class SeqBlock : Coroutine, IDeferSupport, IInspectableCoroutine
+public class SeqBlock : Coroutine, IInspectableCoroutine
 {
   public VM.ExecState exec = new VM.ExecState();
   public List<DeferBlock> defers = new List<DeferBlock>(2);
@@ -136,14 +131,9 @@ public static void ExitScope(VM.Frame frm, VM.ExecState exec, List<DeferBlock> d
 
     DeferBlock.ExitScope(defers, exec);
   }
-
-  public void RegisterDefer(DeferBlock dfb)
-  {
-    defers.Add(dfb);
-  }
 }
 
-public class ParalBranchBlock : Coroutine, IDeferSupport, IInspectableCoroutine
+public class ParalBranchBlock : Coroutine, IInspectableCoroutine
 {
   public int min_ip;
   public int max_ip;
@@ -199,14 +189,9 @@ public override void Cleanup(VM.Frame frm, VM.ExecState _)
     }
     stack.Clear();
   }
-
-  public void RegisterDefer(DeferBlock dfb)
-  {
-    defers.Add(dfb);
-  }
 }
 
-public class ParalBlock : Coroutine, IBranchyCoroutine, IDeferSupport, IInspectableCoroutine
+public class ParalBlock : Coroutine, IBranchyCoroutine, IInspectableCoroutine
 {
   public int min_ip;
   public int max_ip;
@@ -270,14 +255,9 @@ public void Attach(ICoroutine coro)
   {
     branches.Add((Coroutine)coro);
   }
-
-  public void RegisterDefer(DeferBlock dfb)
-  {
-    defers.Add(dfb);
-  }
 }
 
-public class ParalAllBlock : Coroutine, IBranchyCoroutine, IDeferSupport, IInspectableCoroutine
+public class ParalAllBlock : Coroutine, IBranchyCoroutine, IInspectableCoroutine
 {
   public int min_ip;
   public int max_ip;
diff --git a/src/vm/vm.frame.cs b/src/vm/vm.frame.cs
index fc984648..3c42945c 100644
--- a/src/vm/vm.frame.cs
+++ b/src/vm/vm.frame.cs
@@ -6,7 +6,7 @@ namespace bhl {
 
 public partial class VM : INamedResolver
 {
-  public class Frame : IDeferSupport
+  public class Frame
   {
     public const int MAX_LOCALS = 64;
     public const int MAX_STACK = 32;
@@ -132,11 +132,6 @@ internal void Clear()
       defers.Clear();
     }
 
-    public void RegisterDefer(DeferBlock dfb)
-    {
-      defers.Add(dfb);
-    }
-
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public void ExitScope(VM.Frame _, ExecState exec)
     {