diff --git a/src/proc/control/command-argument-holder.hpp b/src/proc/control/command-argument-holder.hpp
index ba61c0314..72ce6a013 100644
--- a/src/proc/control/command-argument-holder.hpp
+++ b/src/proc/control/command-argument-holder.hpp
@@ -44,31 +44,21 @@
 #define CONTROL_COMMAND_ARGUMENT_HOLDER_H
 
 //#include "pre.hpp"
-//#include "lib/error.hpp"
 #include "proc/control/argument-tuple-accept.hpp"
 #include "proc/control/command-closure.hpp"
 #include "proc/control/memento-tie.hpp"
 #include "lib/opaque-holder.hpp"
 
-//#include <tr1/memory>
-//#include <boost/scoped_ptr.hpp>
-//#include <tr1/functional>
 #include <boost/noncopyable.hpp>
-#include <iostream>
 #include <string>
 
 
 
 namespace control {
   
-//  using lumiera::Symbol;
-//  using std::tr1::shared_ptr;
-//  using boost::scoped_ptr;
-//  using std::tr1::function;
-//  using std::ostream;
   using boost::noncopyable;
-  using std::string;
   using lib::InPlaceBuffer;
+  using std::string;
   
   
   namespace { // empty state marker objects for ArgumentHolder
@@ -94,7 +84,7 @@ namespace control {
       {
         typedef typename CommandSignature<SIG,MEM>::CaptureSig SIG_cap;
         typedef typename CommandSignature<SIG,MEM>::UndoOp_Sig SIG_undo;
-    
+        
         UntiedMemento()
           : MementoTie<SIG,MEM> (function<SIG_undo>(), function<SIG_cap>() )
           { }
@@ -209,7 +199,8 @@ namespace control {
       
       
       /** direct "backdoor" access to stored memento value.
-       *  @note you might access a placeholder when called prior to \c tie(..) */
+       *  @throw LUMIERA_ERROR_MISSING_MEMENTO when invoked
+       *         prior to \c tie(..) and capturing any state */
       MEM&
       memento ()
         {
diff --git a/src/proc/control/memento-tie.hpp b/src/proc/control/memento-tie.hpp
index 3ad17c0fc..dff7467f3 100644
--- a/src/proc/control/memento-tie.hpp
+++ b/src/proc/control/memento-tie.hpp
@@ -192,10 +192,13 @@ namespace control {
       friend bool
       operator== (MementoTie const& m1, MementoTie const& m2)
         {
-          return util::rawComparison(m1.undo_,   m2.undo_    )
-              && util::rawComparison(m1.capture_,m2.capture_ )
-              && (m1.isCaptured_  == m2.isCaptured_)
-              && (!m1.isCaptured_ 
+          return ((!m1.undo_ && !m2.undo_ && !m1.capture_ && !m2.capture_) // either no valid functions 
+                  || ( util::rawComparison(m1.undo_,   m2.undo_    )      //  or identical functions
+                    && util::rawComparison(m1.capture_,m2.capture_ )
+                     )
+                 )
+              && (m1.isCaptured_  == m2.isCaptured_)  // either both not captured or identical state
+              && (!m1.isCaptured_
                   || (m1.memento_ == m2.memento_));
         }
     };
diff --git a/tests/components/proc/control/command-argument-test.cpp b/tests/components/proc/control/command-argument-test.cpp
index 4b62380e6..f5e3f3bde 100644
--- a/tests/components/proc/control/command-argument-test.cpp
+++ b/tests/components/proc/control/command-argument-test.cpp
@@ -136,6 +136,9 @@ namespace test    {
         protocol << "undoIt(time="<<time<<")---state-was-:"<< *memento;
       }
     
+    void dummyU (int,int,int) { }
+    int  dummyC (int u,int o) { return u + rand() % (o-u+1); }
+    
     
     
     void
@@ -256,33 +259,42 @@ namespace test    {
       void
       checkArgumentComparison ()
         {
-          ArgumentHolder<void(), int> one, two;
-          ASSERT (one == two);
+          ArgumentHolder<void(int,int), int> one, two;
+          ASSERT (one == two);               // empty, identically typed argument holders -->equal
           
-          one.memento() = 5;
+          one.tie(dummyU,dummyC)
+              .tieCaptureFunc()(1,9);
+          ASSERT (one != two);               // now one contains captured UNDO state
+          
+          two.tie(dummyU,dummyC)
+              .tieCaptureFunc()(1,9);
+          two.memento() = one.memento();     // put the same UNDO state in both
+          ASSERT (one == two);               // ...makes them equal again 
+          
+          one.bind (1,2);                    // verify argument tuple comparison
           ASSERT (one != two);
+          ASSERT (two != one);
+          ASSERT (!isnil (one));
+          ASSERT ( isnil (two));
           
-          ArgumentHolder<void(int,int), int> three, four;
-          ASSERT (three == four);
-          three.bind (1,2);
-          ASSERT (three != four);
-          ASSERT (four != three);
-          ASSERT (!isnil (three));
-          ASSERT ( isnil (four));
-
-          four.bind (3,4);
-          ASSERT (!isnil (four));
-          ASSERT (three != four);
-          ASSERT (four != three);
+          two.bind (3,4);
+          ASSERT (!isnil (two));
+          ASSERT (one != two);
+          ASSERT (two != one);
           
-          three.bind (3,4);
-          ASSERT (!isnil (three));
-          ASSERT (three == four);
-          ASSERT (four == three);
-          four.memento() = 12345;
-          ASSERT (!isnil (four));
-          ASSERT (three != four);
-          ASSERT (four != three);
+          one.bind (1,4);
+          ASSERT (!isnil (one));
+          ASSERT (one != two);
+          ASSERT (two != one);
+          
+          one.bind (3,4);
+          ASSERT (!isnil (one));
+          ASSERT (one == two);
+          ASSERT (two == one);
+          two.memento() = 12345;
+          ASSERT (!isnil (two));
+          ASSERT (one != two);
+          ASSERT (two != one);
         }
       
       
diff --git a/tests/components/proc/control/memento-tie-test.cpp b/tests/components/proc/control/memento-tie-test.cpp
index 0785e8ba5..20a40e1fa 100644
--- a/tests/components/proc/control/memento-tie-test.cpp
+++ b/tests/components/proc/control/memento-tie-test.cpp
@@ -163,14 +163,14 @@ namespace test    {
          
           MemHolder m22x (m22); // clone copy
           ASSERT (!m22x);
-          ASSERT (m22 == m22x);
+          ASSERT (m22 == m22x); // same functions, no state --> equal
           
           testVal = 0;
-          m22x.tieCaptureFunc() (1 + (rand() % 9)); // produce a random memento value != 0
+          m22x.tieCaptureFunc() (1 + (rand() % 9));   // produce a random memento value != 0
           ASSERT (0 < m22x.getState());
           
           ASSERT (m22 != m22x);
-          m22.tieCaptureFunc() (0); // now get the same value into the memento within m22
+          m22.tieCaptureFunc() (m22x.getState()); // get the same value into the memento within m22
           ASSERT (m22 == m22x);
         }
     };