diff --git a/include/llvm/CodeGen/MachineInstr.h b/include/llvm/CodeGen/MachineInstr.h
index 4d772d8f880..15c4b7878a7 100644
--- a/include/llvm/CodeGen/MachineInstr.h
+++ b/include/llvm/CodeGen/MachineInstr.h
@@ -12,7 +12,7 @@
 #include "llvm/Target/MachineInstrInfo.h"
 #include "llvm/Annotation.h"
 #include <iterator>
-#include <hash_set>
+#include <ext/hash_set>
 class Instruction;
 
 //---------------------------------------------------------------------------