diff --git a/src/core/mac/data_poll_handler.cpp b/src/core/mac/data_poll_handler.cpp
index 9e4e1b53f..f4d61eac8 100644
--- a/src/core/mac/data_poll_handler.cpp
+++ b/src/core/mac/data_poll_handler.cpp
@@ -272,12 +272,17 @@ void DataPollHandler::HandleSentFrame(const Mac::TxFrame &aFrame, Error aError,
             {
                 uint32_t frameCounter;
                 uint8_t  keyId;
+                Error    error;
 
-                IgnoreError(aFrame.GetFrameCounter(frameCounter));
+                error = aFrame.GetFrameCounter(frameCounter);
+                OT_ASSERT(error == kErrorNone);
                 aChild.SetIndirectFrameCounter(frameCounter);
 
-                IgnoreError(aFrame.GetKeyId(keyId));
+                error = aFrame.GetKeyId(keyId);
+                OT_ASSERT(error == kErrorNone);
                 aChild.SetIndirectKeyId(keyId);
+
+                OT_UNUSED_VARIABLE(error);
             }
 
             ExitNow();
diff --git a/src/ncp/ncp_base_mtd.cpp b/src/ncp/ncp_base_mtd.cpp
index 3793c8bf6..59312cfff 100644
--- a/src/ncp/ncp_base_mtd.cpp
+++ b/src/ncp/ncp_base_mtd.cpp
@@ -911,7 +911,7 @@ template <> otError NcpBase::HandlePropertySet<SPINEL_PROP_THREAD_ASSISTING_PORT
     {
         uint16_t port;
 
-        IgnoreError(mDecoder.ReadUint16(port));
+        SuccessOrExit(error = mDecoder.ReadUint16(port));
         SuccessOrExit(error = otIp6AddUnsecurePort(mInstance, port));
     }