diff --git a/core/clingutils/src/TClingUtils.cxx b/core/clingutils/src/TClingUtils.cxx
index 59fb2f5137635..0b1ad3499ae0d 100644
--- a/core/clingutils/src/TClingUtils.cxx
+++ b/core/clingutils/src/TClingUtils.cxx
@@ -54,6 +54,7 @@
 #include "cling/Interpreter/Transaction.h"
 #include "cling/Interpreter/Interpreter.h"
 #include "cling/Utils/AST.h"
+#include "cling/Interpreter/InterpreterAccessRAII.h"
 
 #include "llvm/Support/Path.h"
 #include "llvm/Support/FileSystem.h"
@@ -569,6 +570,9 @@ void TClingLookupHelper::GetPartiallyDesugaredName(std::string &nameLong)
 bool TClingLookupHelper::IsAlreadyPartiallyDesugaredName(const std::string &nondef,
                                                          const std::string &nameLong)
 {
+   // We are going to use and possibly update the interpreter information.
+   cling::InterpreterAccessRAII LockAccess(*fInterpreter);
+
    const cling::LookupHelper& lh = fInterpreter->getLookupHelper();
    clang::QualType t = lh.findType(nondef.c_str(), ToLHDS(WantDiags()));
    if (!t.isNull()) {
@@ -584,6 +588,9 @@ bool TClingLookupHelper::IsAlreadyPartiallyDesugaredName(const std::string &nond
 
 bool TClingLookupHelper::IsDeclaredScope(const std::string &base, bool &isInlined)
 {
+   // We are going to use and possibly update the interpreter information.
+   cling::InterpreterAccessRAII LockAccess(*fInterpreter);
+
    const cling::LookupHelper& lh = fInterpreter->getLookupHelper();
    const clang::Decl *scope = lh.findScope(base.c_str(), ToLHDS(WantDiags()), nullptr);
 
@@ -618,6 +625,9 @@ bool TClingLookupHelper::GetPartiallyDesugaredNameWithScopeHandling(const std::s
 
    if (fAutoParse) fAutoParse(tname.c_str());
 
+   // We are going to use and possibly update the interpreter information.
+   cling::InterpreterAccessRAII LockAccess(*fInterpreter);
+
    // Since we already check via other means (TClassTable which is populated by
    // the dictonary loading, and the gROOT list of classes and enums, which are
    // populated via TProtoClass/Enum), we should be able to disable the autoloading
diff --git a/interpreter/cling/include/cling/Interpreter/InterpreterAccessRAII.h b/interpreter/cling/include/cling/Interpreter/InterpreterAccessRAII.h
new file mode 100644
index 0000000000000..d300615fe4c42
--- /dev/null
+++ b/interpreter/cling/include/cling/Interpreter/InterpreterAccessRAII.h
@@ -0,0 +1,43 @@
+//------------------------------------------------------------------------------
+// CLING - the C++ LLVM-based InterpreterG :)
+// author:  Vassil Vassilev <vvasilev@cern.ch>
+//
+// This file is dual-licensed: you can choose to license it under the University
+// of Illinois Open Source License or the GNU Lesser General Public License. See
+// LICENSE.TXT for details.
+//------------------------------------------------------------------------------
+
+#ifndef CLING_INTERPRETERACCESSRAII_H
+#define CLING_INTERPRETERACCESSRAII_H
+
+#include "cling/Interpreter/Interpreter.h"
+#include "cling/Interpreter/InterpreterCallbacks.h"
+
+namespace cling {
+///\brief Locks and unlocks access to the interpreter.
+struct InterpreterAccessRAII {
+  /// Callbacks used to un/lock.
+  InterpreterCallbacks* fCallbacks;
+  /// Info provided to UnlockCompilationDuringUserCodeExecution().
+  void* fStateInfo = nullptr;
+
+  InterpreterAccessRAII(InterpreterCallbacks* callbacks):
+    fCallbacks(callbacks)
+  {
+    if (fCallbacks)
+      // The return value is alway a nullptr.
+      fStateInfo = fCallbacks->LockCompilationDuringUserCodeExecution();
+  }
+
+  InterpreterAccessRAII(Interpreter& interp):
+    InterpreterAccessRAII(interp.getCallbacks()) {}
+
+  ~InterpreterAccessRAII()
+  {
+    if (fCallbacks)
+      fCallbacks->UnlockCompilationDuringUserCodeExecution(fStateInfo);
+  }
+};
+}
+
+#endif // CLING_ENTERUSERCODERAII_H