diff --git a/src/core/mac/sub_mac.cpp b/src/core/mac/sub_mac.cpp
index 5b4f67e16..fea69f28b 100644
--- a/src/core/mac/sub_mac.cpp
+++ b/src/core/mac/sub_mac.cpp
@@ -328,10 +328,16 @@ void SubMac::ProcessTransmitSecurity(void)
     const ExtAddress *extAddress = nullptr;
     uint8_t           keyIdMode;
 
-    VerifyOrExit(ShouldHandleTransmitSecurity());
     VerifyOrExit(mTransmitFrame.GetSecurityEnabled());
     VerifyOrExit(!mTransmitFrame.IsSecurityProcessed());
 
+    if (!mTransmitFrame.IsARetransmission())
+    {
+        mTransmitFrame.SetKeyId(mKeyId);
+    }
+
+    VerifyOrExit(ShouldHandleTransmitSecurity());
+
     SuccessOrExit(mTransmitFrame.GetKeyIdMode(keyIdMode));
     VerifyOrExit(keyIdMode == Frame::kKeyIdMode1);
 
@@ -341,7 +347,6 @@ void SubMac::ProcessTransmitSecurity(void)
     {
         uint32_t frameCounter = GetFrameCounter();
 
-        mTransmitFrame.SetKeyId(mKeyId);
         mTransmitFrame.SetFrameCounter(frameCounter);
         UpdateFrameCounter(frameCounter + 1);
     }