diff --git a/clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp b/clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp
index 5e2cc207560d..fef086c5a99d 100644
--- a/clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp
+++ b/clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp
@@ -116,9 +116,8 @@ void ExpandModularHeadersPPCallbacks::handleModuleFile(
   if (!MF)
     return;
   // Avoid processing a ModuleFile more than once.
-  if (VisitedModules.count(MF))
+  if (!VisitedModules.insert(MF).second)
     return;
-  VisitedModules.insert(MF);
 
   // Visit all the input files of this module and mark them to record their
   // contents later.