diff --git a/include/llvm/ADT/APInt.h b/include/llvm/ADT/APInt.h
index 25505c836e4..c6256ae8462 100644
--- a/include/llvm/ADT/APInt.h
+++ b/include/llvm/ADT/APInt.h
@@ -21,6 +21,7 @@
 #include <cstring>
 #include <iosfwd>
 #include <string>
+#include <cstring>
 
 namespace llvm {
   class Serializer;