diff --git a/clang-tools-extra/clang-tidy/utils/HeaderGuard.cpp b/clang-tools-extra/clang-tidy/utils/HeaderGuard.cpp
--- a/clang-tools-extra/clang-tidy/utils/HeaderGuard.cpp
+++ b/clang-tools-extra/clang-tidy/utils/HeaderGuard.cpp
@@ -123,12 +123,7 @@
 
     // Emit warnings for headers that are missing guards.
     checkGuardlessHeaders();
-
-    // Clear all state.
-    Macros.clear();
-    Files.clear();
-    Ifndefs.clear();
-    EndIfs.clear();
+    clearAllState();
   }
 
   bool wouldFixEndifComment(StringRef FileName, SourceLocation EndIf,
@@ -255,6 +250,13 @@
   }
 
 private:
+  void clearAllState() {
+    Macros.clear();
+    Files.clear();
+    Ifndefs.clear();
+    EndIfs.clear();
+  }
+
   std::vector<std::pair<Token, const MacroInfo *>> Macros;
   llvm::StringMap<const FileEntry *> Files;
   std::map<const IdentifierInfo *, std::pair<SourceLocation, SourceLocation>>