diff --git a/include/xo/interpreter2/vsm/DVirtualSchematikaMachine.hpp b/include/xo/interpreter2/vsm/DVirtualSchematikaMachine.hpp
index 46de95f3..84070673 100644
--- a/include/xo/interpreter2/vsm/DVirtualSchematikaMachine.hpp
+++ b/include/xo/interpreter2/vsm/DVirtualSchematikaMachine.hpp
@@ -27,17 +27,15 @@ namespace xo {
 
             VsmResult() = default;
             explicit VsmResult(obj<AGCObject> value) : result_{value} {}
-            explicit VsmResult(TokenizerError err) : result_{err} {}
 
-            bool is_value() const { return std::holds_alternative<obj<AGCObject>>(result_); }
-            bool is_tk_error() const { return std::holds_alternative<TokenizerError>(result_); }
-            bool is_eval_error() const;
+            bool is_value() const { return result_; }
+            bool is_error() const;
 
-            const obj<AGCObject> * value() const { return std::get_if<obj<AGCObject>>(&result_); }
-            obj<AGCObject> & value_ref() { return std::get<obj<AGCObject>>(result_); }
+            const obj<AGCObject> * value() const { return &result_; }
+            obj<AGCObject> & value_ref() { return result_; }
 
             /** result of evaluating first expression encountered in input **/
-            std::variant<obj<AGCObject>, TokenizerError> result_;
+            obj<AGCObject> result_;
         };
 
         /** vsm result + reamining span **/
@@ -270,7 +268,9 @@ namespace xo {
             obj<AAllocator> aux_mm_;
 
             /** allocator (likely DX1Collector or similar) for
-             *  expressions and values. Schemaatika reader will use this also
+             *  expressions and values. Schemaatika reader will use this also.
+             *
+             *  Allocations must represent a type that supports GCObject.
              **/
             abox<AAllocator> mm_;
 
diff --git a/src/interpreter2/DVirtualSchematikaMachine.cpp b/src/interpreter2/DVirtualSchematikaMachine.cpp
index 8edc0538..9ceb8fac 100644
--- a/src/interpreter2/DVirtualSchematikaMachine.cpp
+++ b/src/interpreter2/DVirtualSchematikaMachine.cpp
@@ -60,15 +60,9 @@ namespace xo {
     namespace scm {
 
         bool
-        VsmResult::is_eval_error() const
+        VsmResult::is_error() const
         {
-            if (std::holds_alternative<obj<AGCObject>>(result_)) {
-                auto err = obj<AGCObject,DRuntimeError>::from(*(this->value()));
-
-                return err;
-            } else {
-                return false;
-            }
+            return (*this->value() && obj<AGCObject,DRuntimeError>::from(*(this->value())));
         }
 
         namespace {
@@ -191,18 +185,39 @@ namespace xo {
 
             reader_.reset_result();
 
-            auto [expr, remaining, error1]
+            auto [expr, remaining, tk_error]
                 = reader_.read_expr(input, eof);
 
             if (!expr) {
-                /* tokenizer error */
+                if (tk_error.is_error()) {
+                    // tokenizer error -> convert to runtime error
 
-                return VsmResultExt(VsmResult(error1), remaining);
+                    DString * src = DString::from_view(mm_.to_op(), tk_error.src_function());
+                    DString * msg = tk_error.report_to_string(mm_.to_op());
+
+                    auto error = obj<AGCObject,DRuntimeError>(DRuntimeError::_make(mm_.to_op(), src, msg));
+
+                    {
+                        obj<APrintable> error_pr
+                            = FacetRegistry::instance().variant<APrintable,AGCObject>(error);
+
+                        ppconfig ppc;
+                        ppstate_standalone pps(&cout, 0, &ppc);
+                        pps.prettyn(error_pr);
+                    }
+
+                    return VsmResultExt(VsmResult(error), remaining);
+                } else {
+                    // incomplete input
+                    return VsmResultExt(VsmResult(), remaining);
+                }
             }
 
+            // here: have obtained complete input expression
+
             VsmResult evalresult = this->start_eval(expr);
 
-            if (evalresult.is_tk_error()) {
+            if (evalresult.is_error()) {
                 // TODO: print error here
 
                 return VsmResultExt(evalresult, remaining);
@@ -210,19 +225,21 @@ namespace xo {
 
             assert(evalresult.is_value());
 
-            obj<AGCObject> * p_value = std::get_if<obj<AGCObject>>(&(evalresult.result_));
+            obj<AGCObject> value = evalresult.result_;
 
-            assert(p_value);
+            assert(value);
 
-            obj<APrintable> value_pr
-                = FacetRegistry::instance().variant<APrintable,AGCObject>(*p_value);
+            {
+                obj<APrintable> value_pr
+                    = FacetRegistry::instance().variant<APrintable,AGCObject>(value);
 
-            // pretty_toplevel(value_pr, &cout, ppconfig());
-            ppconfig ppc;
-            ppstate_standalone pps(&cout, 0, &ppc);
-            pps.prettyn(value_pr);
+                // pretty_toplevel(value_pr, &cout, ppconfig());
+                ppconfig ppc;
+                ppstate_standalone pps(&cout, 0, &ppc);
+                pps.prettyn(value_pr);
+            }
 
-            return VsmResultExt(VsmResult(*p_value), remaining);
+            return VsmResultExt(VsmResult(value), remaining);
         }
 
         const VsmResult &
diff --git a/src/skrepl/skreplxx.cpp b/src/skrepl/skreplxx.cpp
index 51f9df06..a4f86857 100644
--- a/src/skrepl/skreplxx.cpp
+++ b/src/skrepl/skreplxx.cpp
@@ -230,7 +230,7 @@ namespace xo {
 
         *p_input = res.remaining_;
 
-        return !res.is_tk_error() && !res.is_eval_error();
+        return !res.is_error();
     }
 
     void