diff --git a/src/core/thread/network_data_leader_ftd.cpp b/src/core/thread/network_data_leader_ftd.cpp
index f4f8aa5ce..3e033e0bb 100644
--- a/src/core/thread/network_data_leader_ftd.cpp
+++ b/src/core/thread/network_data_leader_ftd.cpp
@@ -320,7 +320,7 @@ void Leader::HandleCommissioningGet(Coap::Message &aMessage, const Ip6::MessageI
 
 void Leader::SendCommissioningGetResponse(const Coap::Message &   aRequest,
                                           const Ip6::MessageInfo &aMessageInfo,
-                                          uint8_t *               aTlvs,
+                                          const uint8_t *         aTlvs,
                                           uint8_t                 aLength)
 {
     ThreadNetif &  netif = GetNetif();
diff --git a/src/core/thread/network_data_leader_ftd.hpp b/src/core/thread/network_data_leader_ftd.hpp
index 3bca1813e..7b6ba6591 100644
--- a/src/core/thread/network_data_leader_ftd.hpp
+++ b/src/core/thread/network_data_leader_ftd.hpp
@@ -226,7 +226,7 @@ private:
 
     void SendCommissioningGetResponse(const Coap::Message &   aRequest,
                                       const Ip6::MessageInfo &aMessageInfo,
-                                      uint8_t *               aTlvs,
+                                      const uint8_t *         aTlvs,
                                       uint8_t                 aLength);
     void SendCommissioningSetResponse(const Coap::Message &    aRequest,
                                       const Ip6::MessageInfo & aMessageInfo,
diff --git a/src/ncp/ncp_buffer.cpp b/src/ncp/ncp_buffer.cpp
index 911c93497..951a41b98 100644
--- a/src/ncp/ncp_buffer.cpp
+++ b/src/ncp/ncp_buffer.cpp
@@ -154,7 +154,7 @@ uint8_t *NcpFrameBuffer::GetUpdatedBufPtr(uint8_t *aBufPtr, uint16_t aOffset, Di
 }
 
 // Gets the distance between two buffer pointers (adjusts for the wrap-around) given a direction (forward or backward).
-uint16_t NcpFrameBuffer::GetDistance(uint8_t *aStartPtr, uint8_t *aEndPtr, Direction aDirection) const
+uint16_t NcpFrameBuffer::GetDistance(const uint8_t *aStartPtr, const uint8_t *aEndPtr, Direction aDirection) const
 {
     size_t distance = 0;
 
diff --git a/src/ncp/ncp_buffer.hpp b/src/ncp/ncp_buffer.hpp
index b4aef8dfa..dacba8a7d 100644
--- a/src/ncp/ncp_buffer.hpp
+++ b/src/ncp/ncp_buffer.hpp
@@ -595,7 +595,7 @@ private:
     };
 
     uint8_t *GetUpdatedBufPtr(uint8_t *aBufPtr, uint16_t aOffset, Direction aDirection) const;
-    uint16_t GetDistance(uint8_t *aStartPtr, uint8_t *aEndPtr, Direction aDirection) const;
+    uint16_t GetDistance(const uint8_t *aStartPtr, const uint8_t *aEndPtr, Direction aDirection) const;
 
     uint16_t ReadUint16At(uint8_t *aBufPtr, Direction aDirection);
     void     WriteUint16At(uint8_t *aBufPtr, uint16_t aValue, Direction aDirection);