diff --git a/unittests/Tooling/DiagnosticsYamlTest.cpp b/unittests/Tooling/DiagnosticsYamlTest.cpp
index 06b60202b97ecf3577d9e95f9f966c1cf035254a..83e09eaeef2dcf4bb1cf29bcd06bacef17777034 100644
--- a/unittests/Tooling/DiagnosticsYamlTest.cpp
+++ b/unittests/Tooling/DiagnosticsYamlTest.cpp
@@ -18,6 +18,7 @@
 
 using namespace llvm;
 using namespace clang::tooling;
+using clang::tooling::Diagnostic;
 
 static Diagnostic makeDiagnostic(StringRef DiagnosticName,
                                  const std::string &Message, int FileOffset,