diff --git a/include/llvm/CodeGen/InstrForest.h b/include/llvm/CodeGen/InstrForest.h
index 78b74df7d40..1927b337586 100644
--- a/include/llvm/CodeGen/InstrForest.h
+++ b/include/llvm/CodeGen/InstrForest.h
@@ -20,6 +20,7 @@
 #define LLVM_CODEGEN_INSTRFOREST_H
 
 #include "llvm/Instruction.h"
+#include "Support/hash_map"
 
 class Constant;
 class Function;