diff --git a/clingwrapper/src/clingwrapper.cxx b/clingwrapper/src/clingwrapper.cxx
index 91be004e..5b2aca12 100644
--- a/clingwrapper/src/clingwrapper.cxx
+++ b/clingwrapper/src/clingwrapper.cxx
@@ -477,7 +477,7 @@ bool Cppyy::AppendTypesSlow(const std::string &name,
   if (!struct_count)
     Cpp::Declare(code.c_str()); // initialize the trampoline
 
-  std::string var = "__s" + std::to_string(struct_count++);
+  std::string var = "__Cppyy_s" + std::to_string(struct_count++);
   // FIXME: We cannot use silent because it erases our error code from Declare!
   if (!Cpp::Declare(("__Cppyy_AppendTypesSlow<" + name + "> " + var +";\n").c_str(), /*silent=*/false)) {
     TCppType_t varN = Cpp::GetVariableType(Cpp::GetNamed(var.c_str()));
diff --git a/clingwrapper/src/cpp_cppyy.h b/clingwrapper/src/cpp_cppyy.h
index 579ff1bf..49a96b5c 100644
--- a/clingwrapper/src/cpp_cppyy.h
+++ b/clingwrapper/src/cpp_cppyy.h
@@ -311,7 +311,7 @@ namespace Cppyy {
 
     RPY_EXPORTED
     TCppIndex_t  GetGlobalOperator(
-        TCppType_t scope, const std::string& lc, const std::string& rc, const std::string& op) { assert(0 && "GetGlobalOperator");return 0; }
+        TCppType_t scope, const std::string& lc, const std::string& rc, const std::string& op) { assert(0 && "GetGlobalOperator");return -1; }
 
 // method properties ---------------------------------------------------------
     RPY_EXPORTED