diff --git a/xo-interpreter2/include/xo/interpreter2/VirtualSchematikaMachine.hpp b/xo-interpreter2/include/xo/interpreter2/VirtualSchematikaMachine.hpp
index 66a1c1e1..0f58f2c4 100644
--- a/xo-interpreter2/include/xo/interpreter2/VirtualSchematikaMachine.hpp
+++ b/xo-interpreter2/include/xo/interpreter2/VirtualSchematikaMachine.hpp
@@ -75,6 +75,12 @@ namespace xo {
              **/
             void _do_eval_if_else_op();
 
+            /** evaluate a sequence expression
+             *  Require:
+             * - expression in @ref expr_
+             **/
+            void _do_eval_sequence_op();
+
         private:
             /*
              * Some registers are preserved by evaluation:
diff --git a/xo-interpreter2/src/interpreter2/VirtualSchematikaMachine.cpp b/xo-interpreter2/src/interpreter2/VirtualSchematikaMachine.cpp
index fe104f9a..02ed023a 100644
--- a/xo-interpreter2/src/interpreter2/VirtualSchematikaMachine.cpp
+++ b/xo-interpreter2/src/interpreter2/VirtualSchematikaMachine.cpp
@@ -60,6 +60,9 @@ namespace xo {
             case exprtype::ifexpr:
                 _do_eval_if_else_op();
                 break;
+            case exprtype::sequence:
+                _do_eval_sequence_op();
+                break;
             }
         }
 
@@ -107,6 +110,13 @@ namespace xo {
             // not implemented
             assert(false);
         }
+
+        void
+        VirtualSchematikaMachine::_do_eval_sequence_op()
+        {
+            // not implemented
+            assert(false);
+        }
     } /*namespace scm*/
 } /*namespace xo*/