diff --git a/include/llvm/CodeGen/MachineConstantPool.h b/include/llvm/CodeGen/MachineConstantPool.h
index 47148e8dd11..c2c3399adb7 100644
--- a/include/llvm/CodeGen/MachineConstantPool.h
+++ b/include/llvm/CodeGen/MachineConstantPool.h
@@ -23,6 +23,7 @@
 #define LLVM_CODEGEN_MACHINECONSTANTPOOL_H
 
 #include <vector>
+#include <iosfwd>
 
 namespace llvm {