diff --git a/src/core/libs/osnma_msg_receiver.cc b/src/core/libs/osnma_msg_receiver.cc
index c3a7ee65a..9d703bf57 100644
--- a/src/core/libs/osnma_msg_receiver.cc
+++ b/src/core/libs/osnma_msg_receiver.cc
@@ -3225,7 +3225,7 @@ std::vector<uint8_t> osnma_msg_receiver::build_message(Tag& tag) const
 }
 
 
-bool osnma_msg_receiver::verify_tesla_key(std::vector<uint8_t>& key, uint32_t key_gst)
+bool osnma_msg_receiver::verify_tesla_key(const std::vector<uint8_t>& key, uint32_t key_gst)
 {
     uint32_t num_of_hashes_needed{};
     uint32_t GST_SFi = gst_with_offset(d_helper->get_WN(d_GST_Sf), d_helper->get_TOW(d_GST_Sf), -30);  // GST of target key is to be used.
diff --git a/src/core/libs/osnma_msg_receiver.h b/src/core/libs/osnma_msg_receiver.h
index 359a1b2b5..f21479167 100644
--- a/src/core/libs/osnma_msg_receiver.h
+++ b/src/core/libs/osnma_msg_receiver.h
@@ -104,7 +104,7 @@ private:
     bool read_mack_body();
     bool process_mack_block(const std::shared_ptr<OSNMA_msg>& osnma_msg, const std::vector<uint8_t>& allowed_adkds, uint8_t nmas);
     bool set_gst_sf_for_mack(uint32_t WN, uint32_t TOW);
-    bool verify_tesla_key(std::vector<uint8_t>& key, uint32_t key_gst);
+    bool verify_tesla_key(const std::vector<uint8_t>& key, uint32_t key_gst);
     bool verify_tag(Tag& tag) const;
     bool tag_has_nav_data_available(const Tag& t) const;
     bool tag_has_key_available(const Tag& t) const;