diff --git a/src/HalfMove.cpp b/src/HalfMove.cpp
index 1375b25..8038acb 100644
--- a/src/HalfMove.cpp
+++ b/src/HalfMove.cpp
@@ -11,7 +11,7 @@ HalfMove::~HalfMove() {
   }
 }
 
-std::string HalfMove::NestedDump(HalfMove *m, int indent) {
+std::string HalfMove::NestedDump(const HalfMove *m, int indent) const{
   std::stringstream ss;
 
   for (int i = 0; i < indent; i++) {
@@ -33,11 +33,11 @@ std::string HalfMove::NestedDump(HalfMove *m, int indent) {
   return (ss.str());
 }
 
-std::string HalfMove::Dump() { return (NestedDump(this, 0)); }
+std::string HalfMove::Dump() const { return (NestedDump(this, 0)); }
 
-int HalfMove::GetLength() {
+int HalfMove::GetLength() const {
   int length = 0;
-  HalfMove *m = this;
+  const HalfMove *m = this;
   while (m != NULL) {
     length++;
     m = m->MainLine;
diff --git a/src/HalfMove.hpp b/src/HalfMove.hpp
index 9e90fda..47caf05 100644
--- a/src/HalfMove.hpp
+++ b/src/HalfMove.hpp
@@ -13,7 +13,7 @@ namespace pgnp {
 class HalfMove {
 private:
   /// @brief Recursive dump
-  std::string NestedDump(HalfMove *, int);
+  std::string NestedDump(const HalfMove *, int) const;
 
 public:
   /// @brief Contains current move count
@@ -33,9 +33,9 @@ public:
   HalfMove();
   ~HalfMove();
   /// @brief Get number of HalfMove in the MailLine
-  int GetLength();
+  int GetLength() const;
   /// @brief Dump move and all its variations
-  std::string Dump();
+  std::string Dump() const;
   /// @brief Perform a deep copy of a HalfMove
   void Copy(HalfMove *copy);
   /// @brief Get HalfMove located x down the MainLine