diff --git a/src/core/coap/coap.cpp b/src/core/coap/coap.cpp
index 94a182162..150332d53 100644
--- a/src/core/coap/coap.cpp
+++ b/src/core/coap/coap.cpp
@@ -746,18 +746,21 @@ exit:
 
 void ResponsesQueue::EnqueueResponse(Message &aMessage, const Ip6::MessageInfo &aMessageInfo)
 {
-    Message *              copy;
+    otError                error          = OT_ERROR_NONE;
+    Message *              cachedResponse = NULL;
+    Message *              responseCopy   = NULL;
     EnqueuedResponseHeader enqueuedResponseHeader(aMessageInfo);
     uint16_t               messageCount;
     uint16_t               bufferCount;
 
-    switch (GetMatchedResponseCopy(aMessage, aMessageInfo, &copy))
+    switch (GetMatchedResponseCopy(aMessage, aMessageInfo, &cachedResponse))
     {
     case OT_ERROR_NOT_FOUND:
         break;
 
     case OT_ERROR_NONE:
-        copy->Free();
+        assert(cachedResponse != NULL);
+        cachedResponse->Free();
 
         // fall through
 
@@ -773,10 +776,10 @@ void ResponsesQueue::EnqueueResponse(Message &aMessage, const Ip6::MessageInfo &
         DequeueOldestResponse();
     }
 
-    VerifyOrExit((copy = aMessage.Clone()) != NULL);
+    VerifyOrExit((responseCopy = aMessage.Clone()) != NULL);
 
-    enqueuedResponseHeader.AppendTo(*copy);
-    mQueue.Enqueue(*copy);
+    SuccessOrExit(error = enqueuedResponseHeader.AppendTo(*responseCopy));
+    mQueue.Enqueue(*responseCopy);
 
     if (!mTimer.IsRunning())
     {
@@ -784,6 +787,12 @@ void ResponsesQueue::EnqueueResponse(Message &aMessage, const Ip6::MessageInfo &
     }
 
 exit:
+
+    if (error != OT_ERROR_NONE && responseCopy != NULL)
+    {
+        responseCopy->Free();
+    }
+
     return;
 }