diff --git a/include/llvm/Support/Format.h b/include/llvm/Support/Format.h
index 0b4bea875b6..8e163ddfd89 100644
--- a/include/llvm/Support/Format.h
+++ b/include/llvm/Support/Format.h
@@ -24,6 +24,7 @@
 #define LLVM_SUPPORT_FORMAT_H
 
 #include "llvm/ADT/StringRef.h"
+#include "llvm/Support/DataTypes.h"
 
 #include <cassert>
 #include <cstdio>