diff --git a/src/core/system_parameters/gnss_crypto.cc b/src/core/system_parameters/gnss_crypto.cc
index 0492b1d23..eab8ab23e 100644
--- a/src/core/system_parameters/gnss_crypto.cc
+++ b/src/core/system_parameters/gnss_crypto.cc
@@ -564,7 +564,7 @@ bool Gnss_Crypto::verify_signature(const std::vector<uint8_t>& message, const st
 }
 
 
-std::vector<uint8_t> Gnss_Crypto::getMerkleRoot(const std::vector<std::vector<uint8_t>>& merkle)
+std::vector<uint8_t> Gnss_Crypto::getMerkleRoot(const std::vector<std::vector<uint8_t>>& merkle) const
 {
     if (merkle.empty())
         {
diff --git a/src/core/system_parameters/gnss_crypto.h b/src/core/system_parameters/gnss_crypto.h
index 83137f15e..c544020a9 100644
--- a/src/core/system_parameters/gnss_crypto.h
+++ b/src/core/system_parameters/gnss_crypto.h
@@ -49,7 +49,7 @@ public:
     bool verify_signature(const std::vector<uint8_t>& message, const std::vector<uint8_t>& signature);
     void readPublicKeyFromPEM(const std::string& pemFilePath);
     void read_merkle_xml(const std::string& merkleFilePath);
-    std::vector<uint8_t> getMerkleRoot(const std::vector<std::vector<uint8_t>>& merkle);
+    std::vector<uint8_t> getMerkleRoot(const std::vector<std::vector<uint8_t>>& merkle) const;
 
     // void set_public_key(const std::vector<uint8_t>& publickey);