diff --git a/clang-tools-extra/clangd/refactor/tweaks/RemoveUsingNamespace.cpp b/clang-tools-extra/clangd/refactor/tweaks/RemoveUsingNamespace.cpp
--- a/clang-tools-extra/clangd/refactor/tweaks/RemoveUsingNamespace.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/RemoveUsingNamespace.cpp
@@ -155,6 +155,13 @@
             if (!visibleContext(T->getDeclContext())
                      ->Equals(TargetDirective->getNominatedNamespace()))
               return;
+            // Avoid adding qualifiers before operators, e.g.
+            //   using namespace std;
+            //   cout << "foo"; // Must not changed to std::cout std:: << "foo"
+            // FIXME: Operators declared in a class context are not handled
+            if (T->isInIdentifierNamespace(
+                    Decl::IdentifierNamespace::IDNS_NonMemberOperator))
+              return;
           }
           SourceLocation Loc = Ref.NameLoc;
           if (Loc.isMacroID()) {