diff --git a/src/core/net/sntp_client.cpp b/src/core/net/sntp_client.cpp
index 2ba966742..575472179 100644
--- a/src/core/net/sntp_client.cpp
+++ b/src/core/net/sntp_client.cpp
@@ -347,10 +347,10 @@ void Client::HandleUdpReceive(Message &aMessage, const Ip6::MessageInfo &aMessag
     // Check the Kiss-o'-death packet.
     if (!responseHeader.GetStratum())
     {
-        char kissCode[Header::GetKissCodeLength() + 1];
+        char kissCode[Header::kKissCodeLength + 1];
 
-        memcpy(kissCode, responseHeader.GetKissCode(), Header::GetKissCodeLength());
-        kissCode[Header::GetKissCodeLength()] = 0;
+        memcpy(kissCode, responseHeader.GetKissCode(), Header::kKissCodeLength);
+        kissCode[Header::kKissCodeLength] = 0;
 
         otLogInfoIp6("SNTP response contains the Kiss-o'-death packet with %s code", kissCode);
         ExitNow(error = OT_ERROR_BUSY);
diff --git a/src/core/net/sntp_client.hpp b/src/core/net/sntp_client.hpp
index 6af1ed909..ccef720aa 100644
--- a/src/core/net/sntp_client.hpp
+++ b/src/core/net/sntp_client.hpp
@@ -31,6 +31,7 @@
 
 #include "openthread-core-config.h"
 
+#include <limits.h>
 #include <openthread/sntp.h>
 
 #include "common/message.hpp"
@@ -76,6 +77,15 @@ public:
         kModeServer = 4,
     };
 
+    /**
+     * Kiss code length.
+     *
+     */
+    enum
+    {
+        kKissCodeLength = 4, ///< Length of the kiss code in ASCII format
+    };
+
     /**
      * This method returns the flags field value.
      *
@@ -204,14 +214,6 @@ public:
      */
     char *GetKissCode(void) { return reinterpret_cast<char *>(&mReferenceId); }
 
-    /**
-     * This method returns the length of the kiss code in ASCII format.
-     *
-     * @returns The length of the kiss code in ASCII format.
-     *
-     */
-    static uint16_t GetKissCodeLength(void) { return sizeof(uint32_t); };
-
     /**
      * This method returns the reference timestamp seconds field.
      *
diff --git a/third_party/NordicSemiconductor/libraries/crypto/nrf52840-mbedtls-config.h b/third_party/NordicSemiconductor/libraries/crypto/nrf52840-mbedtls-config.h
index 0aeb396af..6ae51322c 100644
--- a/third_party/NordicSemiconductor/libraries/crypto/nrf52840-mbedtls-config.h
+++ b/third_party/NordicSemiconductor/libraries/crypto/nrf52840-mbedtls-config.h
@@ -38,4 +38,5 @@
 
 #if defined(__CC_ARM)
     _Pragma("diag_suppress=550")
+    _Pragma("diag_suppress=68")
 #endif