diff --git a/mozilla/modules/libpr0n/decoders/jpeg/nsJPEGDecoder.cpp b/mozilla/modules/libpr0n/decoders/jpeg/nsJPEGDecoder.cpp
index 63f8f9cc452..5ceaeade3ef 100644
--- a/mozilla/modules/libpr0n/decoders/jpeg/nsJPEGDecoder.cpp
+++ b/mozilla/modules/libpr0n/decoders/jpeg/nsJPEGDecoder.cpp
@@ -819,5 +819,8 @@ term_source (j_decompress_ptr jd)
     src->decoder->mObserver->OnStopDecode(nsnull, nsnull, NS_OK, nsnull);
   }
 
-  src->decoder->mFrame->SetMutable(PR_FALSE);
+  PRBool isMutable = PR_FALSE;
+  if (src->decoder->mImageLoad) 
+      src->decoder->mImageLoad->GetIsMultiPartChannel(&isMutable);
+  src->decoder->mFrame->SetMutable(isMutable);
 }
diff --git a/mozilla/modules/libpr0n/public/imgILoad.idl b/mozilla/modules/libpr0n/public/imgILoad.idl
index b084bfd1e71..c88d831f979 100644
--- a/mozilla/modules/libpr0n/public/imgILoad.idl
+++ b/mozilla/modules/libpr0n/public/imgILoad.idl
@@ -41,4 +41,5 @@ interface imgILoad : nsISupports
    * @attention NEED DOCS
    */
   attribute imgIContainer image;
+  readonly attribute PRBool isMultiPartChannel;
 };
diff --git a/mozilla/modules/libpr0n/src/imgRequest.cpp b/mozilla/modules/libpr0n/src/imgRequest.cpp
index 151d11aed44..099847eadb0 100644
--- a/mozilla/modules/libpr0n/src/imgRequest.cpp
+++ b/mozilla/modules/libpr0n/src/imgRequest.cpp
@@ -58,7 +58,7 @@ imgRequest::imgRequest() :
   mObservers(0),
   mLoading(PR_FALSE), mProcessing(PR_FALSE),
   mImageStatus(imgIRequest::STATUS_NONE), mState(0),
-  mContentType(nsnull), mCacheId(0), mValidator(nsnull)
+  mContentType(nsnull), mCacheId(0), mValidator(nsnull), mIsMultiPartChannel(PR_FALSE)
 {
   NS_INIT_ISUPPORTS();
   /* member initializers and constructor code */
@@ -307,6 +307,14 @@ NS_IMETHODIMP imgRequest::GetImage(imgIContainer **aImage)
   return NS_OK;
 }
 
+NS_IMETHODIMP imgRequest::GetIsMultiPartChannel(PRBool *aIsMultiPartChannel)
+{
+  LOG_FUNC(gImgLog, "imgRequest::GetIsMultiPartChannel");
+
+  *aIsMultiPartChannel = mIsMultiPartChannel;
+
+  return NS_OK;
+}
 
 /** imgIContainerObserver methods **/
 
@@ -534,6 +542,11 @@ NS_IMETHODIMP imgRequest::OnStartRequest(nsIRequest *aRequest, nsISupports *ctxt
     mChannel = do_QueryInterface(aRequest);
   }
 
+  nsXPIDLCString mContentType;
+  mChannel->GetContentType(getter_Copies(mContentType));
+  if (PL_strcasecmp("multipart/x-mixed-replace", mContentType.get()) == 0)
+      mIsMultiPartChannel = PR_TRUE;
+
   /* set our state variables to their initial values. */
   mImageStatus = imgIRequest::STATUS_NONE;
   mState = 0;
diff --git a/mozilla/modules/libpr0n/src/imgRequest.h b/mozilla/modules/libpr0n/src/imgRequest.h
index e08ec27827e..63b53df5b25 100644
--- a/mozilla/modules/libpr0n/src/imgRequest.h
+++ b/mozilla/modules/libpr0n/src/imgRequest.h
@@ -128,6 +128,7 @@ private:
   PRTime mLoadTime;
 
   httpValidateChecker *mValidator;
+  PRBool   mIsMultiPartChannel;
 };
 
 #endif