diff --git a/modules/seq/base/src/hmm.cc b/modules/seq/base/src/hmm.cc
index ef0ab66ca200ca733f39894e88252c028f7d69b6..b009f61a05d9e417703b2f848a80cb5462f8db0e 100644
--- a/modules/seq/base/src/hmm.cc
+++ b/modules/seq/base/src/hmm.cc
@@ -8,7 +8,7 @@
 
 namespace ost { namespace seq{ 
 
-int HMMColumn::GetIndex(char olc) const {
+int HMMColumn::GetIndex(char olc){
   if (olc == 'A') return 0;
   if (olc >= 'C' && olc <= 'I') return (olc-'A') - 1;
   if (olc >= 'K' && olc <= 'N') return (olc-'A') - 2;
@@ -61,7 +61,7 @@ Real HMMColumn::GetEntropy() const {
 }
 
 Real HMMColumn::GetFreq(char ch) const{
-  int idx = this->GetIndex(ch);
+  int idx = HMMColumn::GetIndex(ch);
   if(idx == -1){
     throw std::runtime_error("Invalid One Letter Code observed when getting frequency in HMMColumn!");
   }
@@ -69,7 +69,7 @@ Real HMMColumn::GetFreq(char ch) const{
 }
 
 void HMMColumn::SetFreq(char ch, Real freq){
-  int idx = this->GetIndex(ch);
+  int idx = HMMColumn::GetIndex(ch);
   if(idx == -1){
     throw std::runtime_error("Invalid One Letter Code observed when setting frequency in HMMColumn!");
   }
diff --git a/modules/seq/base/src/hmm.hh b/modules/seq/base/src/hmm.hh
index 5fc755797df853378f4a5aa1bbf790e5c9d77d31..408dc5bc6734e02a58d45576c0ffb32cdb0e3d98 100644
--- a/modules/seq/base/src/hmm.hh
+++ b/modules/seq/base/src/hmm.hh
@@ -78,6 +78,7 @@ class HMMColumn {
   char GetOneLetterCode() const { return olc_; }
   void SetOneLetterCode(char olc) { olc_ = olc; }
   Real GetEntropy() const;
+  static int GetIndex(char ch);
 
   static HMMColumn BLOSUMNullModel();
 
@@ -167,7 +168,6 @@ class HMMColumn {
   }
 
  private:
-  int GetIndex(char ch) const;
   char olc_;
   Real freq_[20];
   Real trans_[3][3];