diff --git a/src/lib/iter-tree-explorer.hpp b/src/lib/iter-tree-explorer.hpp
index 073f0a8a4..b716fa6e4 100644
--- a/src/lib/iter-tree-explorer.hpp
+++ b/src/lib/iter-tree-explorer.hpp
@@ -258,6 +258,13 @@ namespace lib {
               >
       { };
     
+    template<class SRC>
+    struct shall_use_Lumiera_Iter
+      : __and_<can_IterForEach<SRC>
+              ,__not_<is_StateCore<SRC>>
+              >
+      { };
+    
     
     template<class SRC, typename SEL=void>
     struct _TreeExplorerTraits
@@ -273,7 +280,7 @@ namespace lib {
       };
     
     template<class SRC>
-    struct _TreeExplorerTraits<SRC,   enable_if<can_IterForEach<SRC>>>
+    struct _TreeExplorerTraits<SRC,   enable_if<shall_use_Lumiera_Iter<SRC>>>
       {
         using SrcIter = typename std::remove_reference<SRC>::type;
       };
diff --git a/tests/library/iter-tree-explorer-test.cpp b/tests/library/iter-tree-explorer-test.cpp
index 92f8900ca..fbf8c084a 100644
--- a/tests/library/iter-tree-explorer-test.cpp
+++ b/tests/library/iter-tree-explorer-test.cpp
@@ -354,11 +354,17 @@ namespace test{
           // test routine called the expansion functor five times
           CHECK (5 == childBuffer.size());
           
+          
           verify_treeExpandingIterator(
                     treeExplore(CountDown{5})
                       .expand([](CountDown const& core){ return CountDown{ yield(core) - 1}; })
                       );
           
+          verify_treeExpandingIterator(
+                    treeExplore(CountDown{5})
+                      .expand([](CountDown const& core){ return NumberSequence{ yield(core) - 1}; })
+                      );
+          
 #if false /////////////////////////////////////////////////////////////////////////////////////////////////////////////TICKET #1118 : GDB Segfault on loading the inferior
           /////////////////////////////////////////////////////////////////////////////////////////////////////////////TICKET #1118 : Generated code works just fine and passes Test though
 #endif    /////////////////////////////////////////////////////////////////////////////////////////////////////////////TICKET #1118 : GDB Segfault on loading the inferior
@@ -366,6 +372,11 @@ namespace test{
                     treeExplore(CountDown{5})
                       .expand([](auto & it){ return CountDown{ *it - 1}; })
                       );
+          
+          verify_treeExpandingIterator(
+                    treeExplore(CountDown{5})
+                      .expand([](auto it){ return decltype(it){ *it - 1}; })
+                      );
         }
       
       
diff --git a/wiki/thinkPad.ichthyo.mm b/wiki/thinkPad.ichthyo.mm
index 8a6c3c259..87fb3d6fd 100644
--- a/wiki/thinkPad.ichthyo.mm
+++ b/wiki/thinkPad.ichthyo.mm
@@ -5361,9 +5361,8 @@
 <icon BUILTIN="button_ok"/>
 </node>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1511227861867" ID="ID_1821706302" MODIFIED="1511571641506" TEXT="Fall-2 ">
-<icon BUILTIN="flag-yellow"/>
-<icon BUILTIN="pencil"/>
+<node COLOR="#338800" CREATED="1511227861867" ID="ID_1821706302" MODIFIED="1511755074830" TEXT="Fall-2 ">
+<icon BUILTIN="button_ok"/>
 <node CREATED="1511227870346" ID="ID_797579225" MODIFIED="1511571541045" TEXT="verzahnte Implementierung">
 <icon BUILTIN="info"/>
 </node>
@@ -5371,12 +5370,17 @@
 <node COLOR="#338800" CREATED="1511227917971" ID="ID_200983707" MODIFIED="1511571722416" TEXT="Core&amp; -&gt; Core">
 <icon BUILTIN="button_ok"/>
 </node>
-<node CREATED="1511227902005" ID="ID_1992381343" MODIFIED="1511571866703" TEXT="Core -&gt; Iter&lt;Val&gt;"/>
-<node CREATED="1511571746395" ID="ID_1199592659" MODIFIED="1511571759405" TEXT="generisches Lambda">
+<node COLOR="#338800" CREATED="1511227902005" ID="ID_1992381343" MODIFIED="1511754553025" TEXT="Core -&gt; Iter&lt;Val&gt;">
+<icon BUILTIN="button_ok"/>
+</node>
+<node CREATED="1511571746395" ID="ID_1199592659" MODIFIED="1511755064482" TEXT="generisches Lambda">
+<icon BUILTIN="button_ok"/>
 <node COLOR="#338800" CREATED="1511227944392" ID="ID_881609766" MODIFIED="1511571897315" TEXT="Iter&lt;Val&gt;&amp; -&gt; Core">
 <icon BUILTIN="button_ok"/>
 </node>
-<node CREATED="1511227925202" ID="ID_290152631" MODIFIED="1511571917720" TEXT="Iter&lt;Val&gt; -&gt; Iter&lt;Val&gt;"/>
+<node COLOR="#338800" CREATED="1511227925202" ID="ID_290152631" MODIFIED="1511755056399" TEXT="Iter&lt;Val&gt; -&gt; Iter&lt;Val&gt;">
+<icon BUILTIN="button_ok"/>
+</node>
 </node>
 </node>
 </node>