diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index a7b5fa7..e92672a 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -1727,6 +1727,7 @@
                                 diag::warn_module_config_mismatch)
             << ModuleFileName;
       // Fall through to error out.
+      LLVM_FALLTHROUGH;
     case ASTReader::VersionMismatch:
     case ASTReader::HadErrors:
       ModuleLoader::HadFatalFailure = true;