diff --git a/lldb/unittests/TestingSupport/TestUtilities.cpp b/lldb/unittests/TestingSupport/TestUtilities.cpp
index 9e5523e4875479..efdc6c5eb234a7 100644
--- a/lldb/unittests/TestingSupport/TestUtilities.cpp
+++ b/lldb/unittests/TestingSupport/TestUtilities.cpp
@@ -19,6 +19,7 @@ using namespace lldb_private;
 
 extern const char *TestMainArgv0;
 
+std::once_flag TestUtilities::g_debugger_initialize_flag;
 std::string lldb_private::GetInputFilePath(const llvm::Twine &name) {
   llvm::SmallString<128> result = llvm::sys::path::parent_path(TestMainArgv0);
   llvm::sys::fs::make_absolute(result);
diff --git a/lldb/unittests/TestingSupport/TestUtilities.h b/lldb/unittests/TestingSupport/TestUtilities.h
index 811c4c1521269b..7d040d64db8d8b 100644
--- a/lldb/unittests/TestingSupport/TestUtilities.h
+++ b/lldb/unittests/TestingSupport/TestUtilities.h
@@ -31,6 +31,11 @@
 namespace lldb_private {
 std::string GetInputFilePath(const llvm::Twine &name);
 
+class TestUtilities {
+public:
+  static std::once_flag g_debugger_initialize_flag;
+};
+
 class TestFile {
 public:
   static llvm::Expected<TestFile> fromYaml(llvm::StringRef Yaml);
@@ -51,6 +56,6 @@ class TestFile {
 
   std::string Buffer;
 };
-}
+} // namespace lldb_private
 
 #endif