diff --git a/src/cpp/ripple/SHAMap.cpp b/src/cpp/ripple/SHAMap.cpp
index ad536e7626..e549b9325b 100644
--- a/src/cpp/ripple/SHAMap.cpp
+++ b/src/cpp/ripple/SHAMap.cpp
@@ -21,13 +21,15 @@ DECLARE_INSTANCE(SHAMap);
 DECLARE_INSTANCE(SHAMapItem);
 DECLARE_INSTANCE(SHAMapTreeNode);
 
+void SHAMapNode::setHash() const
+{
+	std::size_t h = theApp->getNonceST() + mDepth;
+	mHash = mNodeID.hash_combine(h);
+}
+
 std::size_t hash_value(const SHAMapNode& mn)
 {
-	std::size_t seed = theApp->getNonceST();
-
-	boost::hash_combine(seed, mn.getDepth());
-
-	return mn.getNodeID().hash_combine(seed);
+	return mn.getHash();
 }
 
 std::size_t hash_value(const uint256& u)
diff --git a/src/cpp/ripple/SHAMap.h b/src/cpp/ripple/SHAMap.h
index afd323fdd0..a03eb76bd7 100644
--- a/src/cpp/ripple/SHAMap.h
+++ b/src/cpp/ripple/SHAMap.h
@@ -27,23 +27,28 @@ class SHAMap;
 
 
 class SHAMapNode
-{ // Identifies a node in a SHA256 hash
+{ // Identifies a node in a SHA256 hash map
 private:
 	static uint256 smMasks[65]; // AND with hash to get node id
 
 	uint256	mNodeID;
-	int	mDepth;
+	int		mDepth;
+	mutable size_t	mHash;
+
+	void setHash() const;
 
 public:
 
 	static const int rootDepth = 0;
 
-	SHAMapNode() : mDepth(0)			{ ; }
+	SHAMapNode() : mDepth(0), mHash(0)	{ ; }
 	SHAMapNode(int depth, const uint256& hash);
 	virtual ~SHAMapNode()				{ ; }
+
 	int getDepth() const				{ return mDepth; }
 	const uint256& getNodeID()	const	{ return mNodeID; }
 	bool isValid() const { return (mDepth >= 0) && (mDepth < 64); }
+	size_t getHash() const				{ if (mHash == 0) setHash(); return mHash; }
 
 	virtual bool isPopulated() const { return false; }
 
diff --git a/src/cpp/ripple/SHAMapNodes.cpp b/src/cpp/ripple/SHAMapNodes.cpp
index 724f709426..0cfa10b533 100644
--- a/src/cpp/ripple/SHAMapNodes.cpp
+++ b/src/cpp/ripple/SHAMapNodes.cpp
@@ -102,15 +102,16 @@ uint256 SHAMapNode::getNodeID(int depth, const uint256& hash)
 	return hash & smMasks[depth];
 }
 
-SHAMapNode::SHAMapNode(int depth, const uint256 &hash) : mDepth(depth)
+SHAMapNode::SHAMapNode(int depth, const uint256 &hash) : mDepth(depth), mHash(0)
 { // canonicalize the hash to a node ID for this depth
 	assert((depth >= 0) && (depth < 65));
 	mNodeID = getNodeID(depth, hash);
 }
 
-SHAMapNode::SHAMapNode(const void *ptr, int len)
+SHAMapNode::SHAMapNode(const void *ptr, int len) : mHash(0)
 {
-	if (len < 33) mDepth = -1;
+	if (len < 33)
+		mDepth = -1;
 	else
 	{
 		memcpy(mNodeID.begin(), ptr, 32);