diff --git a/unittests/ADT/StringMapTest.cpp b/unittests/ADT/StringMapTest.cpp
index 9f9f2e4..7bb2391 100644
--- a/unittests/ADT/StringMapTest.cpp
+++ b/unittests/ADT/StringMapTest.cpp
@@ -9,6 +9,7 @@
 
 #include "gtest/gtest.h"
 #include "llvm/ADT/StringMap.h"
+#include "llvm/Support/DataTypes.h"
 using namespace llvm;
 
 namespace {