diff --git a/include/llvm/ADT/SmallPtrSet.h b/include/llvm/ADT/SmallPtrSet.h
index 134a7da96c3..ed7f4da4e1a 100644
--- a/include/llvm/ADT/SmallPtrSet.h
+++ b/include/llvm/ADT/SmallPtrSet.h
@@ -17,6 +17,7 @@
 
 #include <cassert>
 #include <cstring>
+#include "llvm/Support/DataTypes.h"
 
 namespace llvm {