diff --git a/src/cpp/ripple/SHAMap.h b/src/cpp/ripple/SHAMap.h
index 21ffc48db..5fec595bb 100644
--- a/src/cpp/ripple/SHAMap.h
+++ b/src/cpp/ripple/SHAMap.h
@@ -4,6 +4,7 @@
 #include <list>
 #include <map>
 #include <stack>
+#include <bitset>
 
 #include <boost/shared_ptr.hpp>
 #include <boost/enable_shared_from_this.hpp>