diff --git a/libzerocash/IncrementalMerkleTree.cpp b/libzerocash/IncrementalMerkleTree.cpp
index 7633dc3..17084a6 100644
--- a/libzerocash/IncrementalMerkleTree.cpp
+++ b/libzerocash/IncrementalMerkleTree.cpp
@@ -25,7 +25,7 @@ namespace libzerocash {
     // IncrementalMerkleTreeCompact class
     /////////////////////////////////////////////
 
-    std::vector<unsigned char> IncrementalMerkleTreeCompact::serialize() {
+    std::vector<unsigned char> IncrementalMerkleTreeCompact::serialize() const {
         /* Serialization format:
          *  treeHeight (4 bytes, big endian)
          *  hashList (ceil(treeHeight / 8) bytes)
@@ -203,7 +203,7 @@ namespace libzerocash {
     }
 
     bool
-    IncrementalMerkleTree::getRootValue(std::vector<bool>& r) {
+    IncrementalMerkleTree::getRootValue(std::vector<bool>& r) const {
 
         // Query the root for its hash
         this->root.getValue(r);
@@ -211,7 +211,7 @@ namespace libzerocash {
     }
 
 	bool
-    IncrementalMerkleTree::getRootValue(std::vector<unsigned char>& r) {
+    IncrementalMerkleTree::getRootValue(std::vector<unsigned char>& r) const {
 
 		// Create a temporary byte vector
 		std::vector<bool> tempR(r.size() * 8, 0);
diff --git a/libzerocash/IncrementalMerkleTree.h b/libzerocash/IncrementalMerkleTree.h
index 0b4b0ef..9d1ae1f 100644
--- a/libzerocash/IncrementalMerkleTree.h
+++ b/libzerocash/IncrementalMerkleTree.h
@@ -45,7 +45,7 @@ class IncrementalMerkleTreeCompact {
     std::vector< std::vector<unsigned char> > const& getHashVec() { return hashVec; }
     std::vector< bool > const& getHashList() { return hashList; }
 
-    std::vector<unsigned char> serialize();
+    std::vector<unsigned char> serialize() const;
     static IncrementalMerkleTreeCompact deserialize(const std::vector<unsigned char>& serialized);
 
 private:
@@ -84,8 +84,8 @@ class IncrementalMerkleNode {
     bool isPruned() const { return subtreePruned; }
     bool hasFreeLeaves() const { return (!subtreeFull); }
     bool hasRightChildren() const { if (!right) return false; return true; }
-    void getValue(std::vector<bool> &r) { r = value; }
-    std::vector<bool>& getValue() { return value; }
+    void getValue(std::vector<bool> &r) const { r = value; }
+    const std::vector<bool>& getValue() const { return value; }
 
     bool checkIfNodeFull();
     void updateHashValue();
@@ -115,12 +115,12 @@ class IncrementalMerkleTree {
 	bool insertElement(const std::vector<unsigned char> &hashV, std::vector<unsigned char> &index);
     bool insertVector(std::vector< std::vector<bool> > &valueVector);
     bool getWitness(const std::vector<bool> &index, merkle_authentication_path &witness);
-    bool getRootValue(std::vector<bool>& r);
-	bool getRootValue(std::vector<unsigned char>& r);
+    bool getRootValue(std::vector<bool>& r) const;
+	bool getRootValue(std::vector<unsigned char>& r) const;
 	std::vector<unsigned char>getRoot();
     bool prune();
     IncrementalMerkleTreeCompact getCompactRepresentation() const;
-    std::vector<unsigned char> serialize() {
+    std::vector<unsigned char> serialize() const {
         auto compact = getCompactRepresentation();
         return compact.serialize();
     }