diff --git a/src/lib/thread.hpp b/src/lib/thread.hpp
index bda68fe5b..9c7ef8f9c 100644
--- a/src/lib/thread.hpp
+++ b/src/lib/thread.hpp
@@ -127,7 +127,7 @@ namespace lib {
   
   namespace thread {// Thread-wrapper base implementation...
     
-    using lib::meta::typeStr;
+    using lib::meta::typeSymbol;
     using std::forward;
     using std::decay_t;
     using std::invoke_result_t;
@@ -313,7 +313,7 @@ namespace lib {
         
         template<class SUB, typename...ARGS>
         ThreadLifecycle (RES (SUB::*memFun) (ARGS...), ARGS ...args)
-          : ThreadLifecycle{util::joinDash (typeStr<SUB>(), args...)
+          : ThreadLifecycle{util::joinDash (typeSymbol<SUB>(), args...)
                            ,std::move (memFun)
                            ,static_cast<SUB*> (this)
                            ,forward<ARGS> (args)... }
diff --git a/tests/library/thread-wrapper-join-test.cpp b/tests/library/thread-wrapper-join-test.cpp
index 1ba9acd68..015510fc8 100644
--- a/tests/library/thread-wrapper-join-test.cpp
+++ b/tests/library/thread-wrapper-join-test.cpp
@@ -27,35 +27,37 @@
 
 #include "lib/test/run.hpp"
 #include "lib/test/test-helper.hpp"
-
 #include "lib/thread.hpp"
 #include "lib/error.hpp"
 
-#include <functional>
+#include <chrono>
 
-using std::bind;
 using test::Test;
-
+using std::this_thread::sleep_for;
+using namespace std::chrono_literals;
 
 
 namespace lib {
 namespace test {
   
-  using lumiera::error::LUMIERA_ERROR_LOGIC;
+  using error::LUMIERA_ERROR_LOGIC;
   namespace {
     
-    const int DESTRUCTION_CODE = 23;
+    const int DESTRUCTION_CODE = -23;
     
-    LUMIERA_ERROR_DEFINE(SPECIAL, "grandiose exception");
+    LUMIERA_ERROR_DEFINE(SPECIAL, "007 exception");
+    
+    #define Type(_EXPR_) lib::test::showType<decltype(_EXPR_)>()
   }
   
   
   /***********************************************************************//**
-   * @test use the Lumiera Vault to create some new threads, additionally
-   *       synchronising with these child threads and waiting for termination.
-   * 
-   * @see vault::Thread
-   * @see threads.h
+   * @test verify the special flavour of the thread-wrapper, allowing to block
+   *       waiting on thread end and then pass result or error state.
+     * @see thread.hpp
+     * @see Result_test
+     * @see ThreadWrapper_test
+     * @see SyncLocking_test
    */
   class ThreadWrapperJoin_test : public Test
     {
@@ -63,52 +65,79 @@ namespace test {
       virtual void
       run (Arg)
         {
-          simpleUse ();
-          wrongUse ();
+          simpleUse();
+          returnValue();
+          detectFailure();
+          joinOnceOnly();
         }
       
       
-      volatile int aValue_;         ///< state to be modified by the other thread
-      
       void
+      simpleUse()
+        {
+          ThreadJoinable theThread{"test join-1"
+                                  ,[]{ sleep_for (10ms); }};
+          CHECK (theThread);
+          theThread.join();     // blocks until thread-function has terminated
+          CHECK (not theThread);
+        }
+      
+      
+      
+      int
       theAction (int secretValue)   ///< to be run in a new thread...
         {
-          usleep (100000);          // pause 100ms prior to modifying
+          sleep_for (100ms);        // pause 100ms prior to modifying
           
           if (DESTRUCTION_CODE == secretValue)
-            LUMIERA_ERROR_SET(test, SPECIAL, 0);
+            throw error::External{"special agent detected"
+                                 , LUMIERA_ERROR_SPECIAL};
           else
-            aValue_ =  secretValue+42;
-          
-          
+            return secretValue+42;
         }
       
       
       void
-      simpleUse ()
+      returnValue()
         {
-          aValue_=0;
-          int mySecret = (rand() % 1000) - 500;
+          int mySecret = rand() % 1000;
           
-          ThreadJoinable newThread("test Thread joining-1"
-                                  , bind (&ThreadWrapperJoin_test::theAction, this, mySecret)
-                                  );
-          newThread.join();      // blocks until theAction() is done
-          
-          CHECK (aValue_ == mySecret+42);
+          ThreadJoinable theThread{"test join-2"
+                                  ,&ThreadWrapperJoin_test::theAction
+                                  , this, mySecret};
+         
+          // Note: join() passes the result value captured in the thread
+          CHECK (mySecret+42 == theThread.join());
         }
       
       
       void
-      wrongUse ()
+      detectFailure()
         {
-          ThreadJoinable newThread("test Thread joining-2"
-                                  , bind (&ThreadWrapperJoin_test::theAction, this, 1234)
-                                  );
-          newThread.join();      // blocks until theAction() is done
+          ThreadJoinable theThread{"test join-3"
+                                  ,&ThreadWrapperJoin_test::theAction
+                                  , this, DESTRUCTION_CODE};
+         
+          // join() actually returns a proxy...
+          auto res = theThread.join();
+          CHECK (Type(res) == "Result<int>"_expect);
           
-          VERIFY_ERROR(LOGIC, newThread.join() );
-          VERIFY_ERROR(LOGIC, newThread.join() );
+          // can detect that the thread was aborted with an exception
+          CHECK (not res.isValid());
+          VERIFY_ERROR(SPECIAL, res.maybeThrow() );
+          VERIFY_ERROR(SPECIAL, (int)res );
+        }
+      
+      
+      void
+      joinOnceOnly ()
+        {
+          ThreadJoinable theThread{"joining-4"
+                                  ,[]{ sleep_for (10ms); }};
+          theThread.join();
+          
+          VERIFY_ERROR(LOGIC, theThread.join() );
+          VERIFY_ERROR(LOGIC, theThread.join() );
         }
     };
   
diff --git a/tests/library/thread-wrapper-test.cpp b/tests/library/thread-wrapper-test.cpp
index 38ded9666..8eb8088ae 100644
--- a/tests/library/thread-wrapper-test.cpp
+++ b/tests/library/thread-wrapper-test.cpp
@@ -124,7 +124,7 @@ namespace test{
                                       {
                                         uint x = rand() % 1000;
                                         globalSum += (i + x);
-                                        threads.emplace<TestThread> (&TestThread::doIt, uint{i}, uint{x});
+                                        threads.emplace<TestThread> (&TestThread::doIt, i, x);
                                       }                            // Note: bind to member function, copying arguments
                                     
                                     while (explore(threads).has_any())
diff --git a/wiki/thinkPad.ichthyo.mm b/wiki/thinkPad.ichthyo.mm
index 69d813c69..5538263d1 100644
--- a/wiki/thinkPad.ichthyo.mm
+++ b/wiki/thinkPad.ichthyo.mm
@@ -79026,9 +79026,12 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 <node CREATED="1695392987999" ID="ID_109089425" MODIFIED="1695393002077" TEXT="wird (derzeit und absehbar) nur f&#xfc;r Tests verwendet">
 <icon BUILTIN="info"/>
 <node CREATED="1695393029161" ID="ID_1726147640" MODIFIED="1695393053763" TEXT="und daf&#xfc;r ist auch die Fehler-Weitergabe sinnvoll"/>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1695393054345" ID="ID_582803458" MODIFIED="1695393067033" TEXT="also auch dieses Zusatz-Feature erhalten">
+<node COLOR="#435e98" CREATED="1695393054345" ID="ID_582803458" MODIFIED="1696015399487" TEXT="also auch dieses Zusatz-Feature erhalten">
 <icon BUILTIN="yes"/>
 </node>
+<node COLOR="#435e98" CREATED="1696015411959" ID="ID_399469746" MODIFIED="1696015426502" TEXT="ausgebaut: kann nun sogar Ergebniswert transportieren">
+<icon BUILTIN="idea"/>
+</node>
 </node>
 </node>
 <node CREATED="1695313818614" ID="ID_470584516" MODIFIED="1695313837839" TEXT="Thread::syncPoint() / sync()">
@@ -79263,8 +79266,8 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 </node>
 </node>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1695394188133" ID="ID_1229328590" MODIFIED="1695394203632" TEXT="Umbau">
-<icon BUILTIN="flag-yellow"/>
+<node BACKGROUND_COLOR="#eef0c5" COLOR="#990000" CREATED="1695394188133" ID="ID_1229328590" MODIFIED="1696015383325" TEXT="Umbau">
+<icon BUILTIN="pencil"/>
 <node COLOR="#338800" CREATED="1695597011139" ID="ID_125138411" MODIFIED="1695859127749" TEXT="Kopie des bestehenden Thread-Wrappers umschreiben">
 <linktarget COLOR="#6ebe5a" DESTINATION="ID_125138411" ENDARROW="Default" ENDINCLINATION="43;-18;" ID="Arrow_ID_195305087" SOURCE="ID_215388471" STARTARROW="None" STARTINCLINATION="-113;6;"/>
 <icon BUILTIN="button_ok"/>
@@ -79949,8 +79952,8 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 <icon BUILTIN="button_ok"/>
 </node>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1695394205547" ID="ID_1719816317" MODIFIED="1695394259544" TEXT="Tests umstellen und modernisieren">
-<icon BUILTIN="flag-yellow"/>
+<node BACKGROUND_COLOR="#eef0c5" COLOR="#990000" CREATED="1695394205547" ID="ID_1719816317" MODIFIED="1696015377362" TEXT="Tests umstellen und modernisieren">
+<icon BUILTIN="pencil"/>
 <node COLOR="#338800" CREATED="1695394270093" ID="ID_585437655" MODIFIED="1696007768225" TEXT="ThreadWrapper_test">
 <icon BUILTIN="button_ok"/>
 <node COLOR="#338800" CREATED="1695911786871" ID="ID_1371513124" MODIFIED="1695911794232" TEXT="l&#xe4;uft nach Umstellung">
@@ -80017,16 +80020,24 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 <icon BUILTIN="button_ok"/>
 </node>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1695394665822" ID="ID_881973960" MODIFIED="1695394668399" TEXT="ThreadWrapperJoin_test">
-<icon BUILTIN="flag-yellow"/>
+<node COLOR="#338800" CREATED="1695394665822" ID="ID_881973960" MODIFIED="1696015353416" TEXT="ThreadWrapperJoin_test">
+<icon BUILTIN="button_ok"/>
 <node COLOR="#338800" CREATED="1695911786871" ID="ID_1004221223" MODIFIED="1695911801372" TEXT="l&#xe4;uft nach Umstellung">
 <icon BUILTIN="button_ok"/>
 </node>
-<node CREATED="1695394703974" ID="ID_1918931115" MODIFIED="1695394714328" TEXT="erscheint bereits ad&#xe4;quat">
+<node COLOR="#5b280f" CREATED="1695394703974" ID="ID_1918931115" MODIFIED="1696015368741" TEXT="erscheint bereits ad&#xe4;quat">
 <icon BUILTIN="yes"/>
+<icon BUILTIN="button_cancel"/>
 </node>
-<node BACKGROUND_COLOR="#f0d5c5" COLOR="#990033" CREATED="1695394715296" ID="ID_1135505355" MODIFIED="1695394724096" TEXT="pr&#xfc;fen: ggfs Fehlercode durchgeben?">
-<icon BUILTIN="help"/>
+<node COLOR="#338800" CREATED="1696009922459" ID="ID_1972276036" MODIFIED="1696015355517" TEXT="modernisieren kann man ihn trotzdem">
+<icon BUILTIN="button_ok"/>
+<node COLOR="#435e98" CREATED="1696009997026" ID="ID_674091759" MODIFIED="1696015360374" TEXT="&#x3bb; binden"/>
+<node COLOR="#435e98" CREATED="1696010004869" ID="ID_819043932" MODIFIED="1696015360374" TEXT="warten per chrono-Angabe"/>
+</node>
+<node COLOR="#338800" CREATED="1696010020799" ID="ID_698469449" MODIFIED="1696015357116" TEXT="neue Funktionalit&#xe4;t abdecken">
+<icon BUILTIN="button_ok"/>
+<node COLOR="#435e98" CREATED="1696010033020" ID="ID_349091998" MODIFIED="1696015360374" TEXT="R&#xfc;ckgabewert"/>
+<node COLOR="#435e98" CREATED="1696010036948" ID="ID_440877573" MODIFIED="1696015360375" TEXT="Fehlerbehandlung"/>
 </node>
 </node>
 <node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1695394744028" ID="ID_1755648327" MODIFIED="1695394746744" TEXT="ThreadWrapperSelfRecognitionTest_test">