diff --git a/include/aidge/utils/Registrar.hpp b/include/aidge/utils/Registrar.hpp
index a5bd260ec189ac998134b738ca1ae757f2a0038c..567270d63c092aef6411a4438f59b7770ee3d5bf 100644
--- a/include/aidge/utils/Registrar.hpp
+++ b/include/aidge/utils/Registrar.hpp
@@ -132,11 +132,13 @@ void declare_registrable(py::module& m, const std::string& class_name){
 #ifdef PYBIND
 #define SET_IMPL_MACRO(T_Op, op, backend_name) \
      \
-        if(Py_IsInitialized()) { \
-            auto obj = py::cast(&(op)); \
-            (op).setImpl(Registrar<T_Op>::create(backend_name)(op)); \
-        } else { \
-            (op).setImpl(Registrar<T_Op>::create(backend_name)(op)); \
+        if (Registrar<T_Op>::exists(backend_name)) { \
+            if(Py_IsInitialized()) { \
+                auto obj = py::cast(&(op)); \
+                (op).setImpl(Registrar<T_Op>::create(backend_name)(op)); \
+            } else { \
+                (op).setImpl(Registrar<T_Op>::create(backend_name)(op)); \
+            } \
         }
 #else
 #define SET_IMPL_MACRO(T_Op, op, backend_name)                          \
diff --git a/src/graphRegex/GraphRegex.cpp b/src/graphRegex/GraphRegex.cpp
index 00a031e3fa9b03ff1870446b9ae58e8d3eb65bf7..ca15ff8dec5ff5ebd4ea69141c6e286849162bb5 100644
--- a/src/graphRegex/GraphRegex.cpp
+++ b/src/graphRegex/GraphRegex.cpp
@@ -117,6 +117,8 @@ std::set<std::shared_ptr<MatchSolution>> GraphRegex::match(std::shared_ptr<Graph
             std::vector<std::shared_ptr<MatchSolution>> solution = fsm->test(combination);
             solutions.insert(solutions.end(), solution.begin(), solution.end());
         }
+
+
     }
     return _findLargestCompatibleSet(solutions);
 }
@@ -142,7 +144,10 @@ void GraphRegex::setNodeKey(const std::string key,std::function<bool(NodePtr)> f
         throw std::runtime_error(key + " is define");
     }
     mAllLambda[key] = f;
+    
     _majConditionalInterpreterLambda();
+    //we add the lambda as key by default 
+    setNodeKey(key, key + "($)==true");
 }
 
 void GraphRegex::_majConditionalInterpreterLambda(){
diff --git a/src/nodeTester/ConditionalLexer.cpp b/src/nodeTester/ConditionalLexer.cpp
index 9379bd8409f8f7ec4bae3e0122f88de79718e9dd..e70772fc1a5d6136fb56f5981d73bf6cb0622991 100644
--- a/src/nodeTester/ConditionalLexer.cpp
+++ b/src/nodeTester/ConditionalLexer.cpp
@@ -120,7 +120,7 @@ std::shared_ptr<ParsingToken<ConditionalTokenTypes>> ConditionalLexer::getNextTo
             }
 
 
-            if (std::regex_match(currentChars,std::regex("(true|false)"))){
+            if (std::regex_match(currentChars,std::regex("(true|false|True|False)"))){
                 return std::make_shared<ParsingToken<ConditionalTokenTypes>>(ConditionalTokenTypes::BOOL,currentChars);
 
             } else if (isLambda){
diff --git a/unit_tests/graphRegex/Test_GraphRegex.cpp b/unit_tests/graphRegex/Test_GraphRegex.cpp
index bcd6d0f4cd9ba32ee4318188343b7e6360670d3b..a62b9a8602b494f26fb47061b899eaba41129a1f 100644
--- a/unit_tests/graphRegex/Test_GraphRegex.cpp
+++ b/unit_tests/graphRegex/Test_GraphRegex.cpp
@@ -18,6 +18,32 @@ using namespace Aidge;
 
 TEST_CASE("GraphRegexUser") {
 
+
+    SECTION("Match using custom lambda") {
+
+        std::shared_ptr<GraphView> g1 = std::make_shared<GraphView>("TestGraph");
+        std::shared_ptr<Node> conv = GenericOperator("Conv", 1, 0, 1, "c");
+        std::shared_ptr<Node> fc = GenericOperator("FC", 1, 0, 1, "c1");
+        std::shared_ptr<Node> conv2 = GenericOperator("Conv", 1, 0, 1, "c2");
+        std::shared_ptr<Node> fc2 = GenericOperator("FC", 1, 0, 1, "c3");
+
+        g1->add(conv);
+        g1->addChild(fc, "c");
+        g1->addChild(conv2, "c1");
+        g1->addChild(fc2, "c2");
+        
+        ///
+        std::shared_ptr<GraphRegex> sut = std::make_shared<GraphRegex>();
+        sut->setNodeKey("C",+[](NodePtr NodeOp){return NodeOp->type() == "FC";});
+        
+        sut->setNodeKey("A","C($)==True");
+        sut->addQuery("A");
+        auto match = sut->match(g1);
+        REQUIRE(match.size() == 2);
+
+    }
+
+
     SECTION("INIT") {
 
         const std::string query = "Conv->FC";