diff --git a/clang-tools-extra/clang-tidy/modernize/UseUsingCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseUsingCheck.cpp
--- a/clang-tools-extra/clang-tidy/modernize/UseUsingCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseUsingCheck.cpp
@@ -16,6 +16,10 @@
 namespace tidy {
 namespace modernize {
 
+AST_MATCHER(Decl, isInExternC) {
+  return Node.getDeclContext()->isExternCContext();
+}
+
 UseUsingCheck::UseUsingCheck(StringRef Name, ClangTidyContext *Context)
     : ClangTidyCheck(Name, Context),
       IgnoreMacros(Options.getLocalOrGlobal("IgnoreMacros", true)) {}
@@ -25,8 +29,10 @@
 }
 
 void UseUsingCheck::registerMatchers(MatchFinder *Finder) {
-  Finder->addMatcher(typedefDecl(unless(isInstantiated())).bind("typedef"),
-                     this);
+  Finder->addMatcher(
+      typedefDecl(unless(isInstantiated()), unless(isInExternC()))
+          .bind("typedef"),
+      this);
   // This matcher used to find tag declarations in source code within typedefs.
   // They appear in the AST just *prior* to the typedefs.
   Finder->addMatcher(tagDecl(unless(isImplicit())).bind("tagdecl"), this);
diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize-use-using.cpp b/clang-tools-extra/test/clang-tidy/checkers/modernize-use-using.cpp
--- a/clang-tools-extra/test/clang-tidy/checkers/modernize-use-using.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/modernize-use-using.cpp
@@ -302,3 +302,10 @@
   // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use 'using' instead of 'typedef'
   // CHECK-FIXES: using b = InjectedClassNameWithUnnamedArgument;
 };
+
+extern "C" {
+typedef int CType;
+typedef struct {
+  int b;
+} CStruct;
+}