diff --git a/image/decoders/nsBMPDecoder.cpp b/image/decoders/nsBMPDecoder.cpp
index 57e4f01ad1ef..35b0db920772 100644
--- a/image/decoders/nsBMPDecoder.cpp
+++ b/image/decoders/nsBMPDecoder.cpp
@@ -38,7 +38,7 @@ GetBMPLog()
 #define LINE(row) ((mBIH.height < 0) ? (-mBIH.height - (row)) : ((row) - 1))
 #define PIXEL_OFFSET(row, col) (LINE(row) * mBIH.width + col)
 
-nsBMPDecoder::nsBMPDecoder(RasterImage& aImage)
+nsBMPDecoder::nsBMPDecoder(RasterImage* aImage)
   : Decoder(aImage)
   , mPos(0)
   , mLOH(WIN_V3_HEADER_LENGTH)
diff --git a/image/decoders/nsBMPDecoder.h b/image/decoders/nsBMPDecoder.h
index 086eee4b5559..7e34576c6997 100644
--- a/image/decoders/nsBMPDecoder.h
+++ b/image/decoders/nsBMPDecoder.h
@@ -23,7 +23,7 @@ class nsBMPDecoder : public Decoder
 {
 public:
 
-    explicit nsBMPDecoder(RasterImage& aImage);
+    explicit nsBMPDecoder(RasterImage* aImage);
     ~nsBMPDecoder();
 
     // Specifies whether or not the BMP file will contain alpha data
diff --git a/image/decoders/nsGIFDecoder2.cpp b/image/decoders/nsGIFDecoder2.cpp
index aad439cc9fa5..2b16e1d23e66 100644
--- a/image/decoders/nsGIFDecoder2.cpp
+++ b/image/decoders/nsGIFDecoder2.cpp
@@ -68,7 +68,7 @@ namespace image {
 //////////////////////////////////////////////////////////////////////
 // GIF Decoder Implementation
 
-nsGIFDecoder2::nsGIFDecoder2(RasterImage& aImage)
+nsGIFDecoder2::nsGIFDecoder2(RasterImage* aImage)
   : Decoder(aImage)
   , mCurrentRow(-1)
   , mLastFlushedRow(-1)
diff --git a/image/decoders/nsGIFDecoder2.h b/image/decoders/nsGIFDecoder2.h
index 04ef594218eb..c40758018a52 100644
--- a/image/decoders/nsGIFDecoder2.h
+++ b/image/decoders/nsGIFDecoder2.h
@@ -23,7 +23,7 @@ class nsGIFDecoder2 : public Decoder
 {
 public:
 
-  explicit nsGIFDecoder2(RasterImage& aImage);
+  explicit nsGIFDecoder2(RasterImage* aImage);
   ~nsGIFDecoder2();
 
   virtual void WriteInternal(const char* aBuffer, uint32_t aCount) MOZ_OVERRIDE;
diff --git a/image/decoders/nsICODecoder.cpp b/image/decoders/nsICODecoder.cpp
index c50541b7f254..102a9ffb70c3 100644
--- a/image/decoders/nsICODecoder.cpp
+++ b/image/decoders/nsICODecoder.cpp
@@ -58,7 +58,7 @@ nsICODecoder::GetNumColors()
 }
 
 
-nsICODecoder::nsICODecoder(RasterImage& aImage)
+nsICODecoder::nsICODecoder(RasterImage* aImage)
  : Decoder(aImage)
 {
   mPos = mImageOffset = mCurrIcon = mNumIcons = mBPP = mRowBytes = 0;
@@ -249,7 +249,7 @@ nsICODecoder::WriteInternal(const char* aBuffer, uint32_t aCount)
   }
 
   uint16_t colorDepth = 0;
-  nsIntSize prefSize = mImage.GetRequestedResolution();
+  nsIntSize prefSize = mImage->GetRequestedResolution();
   if (prefSize.width == 0 && prefSize.height == 0) {
     prefSize.SizeTo(PREFICONSIZE, PREFICONSIZE);
   }
diff --git a/image/decoders/nsICODecoder.h b/image/decoders/nsICODecoder.h
index e8dfece364d4..556aea4a63db 100644
--- a/image/decoders/nsICODecoder.h
+++ b/image/decoders/nsICODecoder.h
@@ -23,7 +23,7 @@ class nsICODecoder : public Decoder
 {
 public:
 
-  explicit nsICODecoder(RasterImage& aImage);
+  explicit nsICODecoder(RasterImage* aImage);
   virtual ~nsICODecoder();
 
   // Obtains the width of the icon directory entry
diff --git a/image/decoders/nsIconDecoder.cpp b/image/decoders/nsIconDecoder.cpp
index a1658e536b40..f4c8335dba26 100644
--- a/image/decoders/nsIconDecoder.cpp
+++ b/image/decoders/nsIconDecoder.cpp
@@ -15,7 +15,7 @@
 namespace mozilla {
 namespace image {
 
-nsIconDecoder::nsIconDecoder(RasterImage& aImage)
+nsIconDecoder::nsIconDecoder(RasterImage* aImage)
  : Decoder(aImage),
    mWidth(-1),
    mHeight(-1),
diff --git a/image/decoders/nsIconDecoder.h b/image/decoders/nsIconDecoder.h
index 358423d29a62..e64f81186ba4 100644
--- a/image/decoders/nsIconDecoder.h
+++ b/image/decoders/nsIconDecoder.h
@@ -38,7 +38,7 @@ class nsIconDecoder : public Decoder
 {
 public:
 
-  explicit nsIconDecoder(RasterImage& aImage);
+  explicit nsIconDecoder(RasterImage* aImage);
   virtual ~nsIconDecoder();
 
   virtual void WriteInternal(const char* aBuffer, uint32_t aCount) MOZ_OVERRIDE;
diff --git a/image/decoders/nsJPEGDecoder.cpp b/image/decoders/nsJPEGDecoder.cpp
index c51c4c341fac..3b48eab551a3 100644
--- a/image/decoders/nsJPEGDecoder.cpp
+++ b/image/decoders/nsJPEGDecoder.cpp
@@ -84,7 +84,7 @@ METHODDEF(void) my_error_exit (j_common_ptr cinfo);
 #define MAX_JPEG_MARKER_LENGTH  (((uint32_t)1 << 16) - 1)
 
 
-nsJPEGDecoder::nsJPEGDecoder(RasterImage& aImage,
+nsJPEGDecoder::nsJPEGDecoder(RasterImage* aImage,
                              Decoder::DecodeStyle aDecodeStyle)
  : Decoder(aImage)
  , mDecodeStyle(aDecodeStyle)
@@ -237,7 +237,7 @@ nsJPEGDecoder::WriteInternal(const char* aBuffer, uint32_t aCount)
         return; // I/O suspension
       }
 
-      int sampleSize = mImage.GetRequestedSampleSize();
+      int sampleSize = mImage->GetRequestedSampleSize();
       if (sampleSize > 0) {
         mInfo.scale_num = 1;
         mInfo.scale_denom = sampleSize;
diff --git a/image/decoders/nsJPEGDecoder.h b/image/decoders/nsJPEGDecoder.h
index 74c1a3d83164..dce35c648700 100644
--- a/image/decoders/nsJPEGDecoder.h
+++ b/image/decoders/nsJPEGDecoder.h
@@ -52,7 +52,7 @@ struct Orientation;
 class nsJPEGDecoder : public Decoder
 {
 public:
-  nsJPEGDecoder(RasterImage& aImage, Decoder::DecodeStyle aDecodeStyle);
+  nsJPEGDecoder(RasterImage* aImage, Decoder::DecodeStyle aDecodeStyle);
   virtual ~nsJPEGDecoder();
 
   virtual void InitInternal() MOZ_OVERRIDE;
diff --git a/image/decoders/nsPNGDecoder.cpp b/image/decoders/nsPNGDecoder.cpp
index 1cd00f87d7f6..2b45e51e1a59 100644
--- a/image/decoders/nsPNGDecoder.cpp
+++ b/image/decoders/nsPNGDecoder.cpp
@@ -107,7 +107,7 @@ nsPNGDecoder::AnimFrameInfo::AnimFrameInfo(png_structp aPNG, png_infop aInfo)
 const uint8_t
 nsPNGDecoder::pngSignatureBytes[] = { 137, 80, 78, 71, 13, 10, 26, 10 };
 
-nsPNGDecoder::nsPNGDecoder(RasterImage& aImage)
+nsPNGDecoder::nsPNGDecoder(RasterImage* aImage)
  : Decoder(aImage),
    mPNG(nullptr), mInfo(nullptr),
    mCMSLine(nullptr), interlacebuf(nullptr),
diff --git a/image/decoders/nsPNGDecoder.h b/image/decoders/nsPNGDecoder.h
index cae9584cbc80..ddcee6230d38 100644
--- a/image/decoders/nsPNGDecoder.h
+++ b/image/decoders/nsPNGDecoder.h
@@ -24,7 +24,7 @@ class RasterImage;
 class nsPNGDecoder : public Decoder
 {
 public:
-  explicit nsPNGDecoder(RasterImage& aImage);
+  explicit nsPNGDecoder(RasterImage* aImage);
   virtual ~nsPNGDecoder();
 
   virtual void InitInternal() MOZ_OVERRIDE;
diff --git a/image/src/Decoder.cpp b/image/src/Decoder.cpp
index 70ef6bee8aeb..cc2c88ee9610 100644
--- a/image/src/Decoder.cpp
+++ b/image/src/Decoder.cpp
@@ -20,7 +20,7 @@ using mozilla::gfx::SurfaceFormat;
 namespace mozilla {
 namespace image {
 
-Decoder::Decoder(RasterImage &aImage)
+Decoder::Decoder(RasterImage* aImage)
   : mImage(aImage)
   , mProgress(NoProgress)
   , mImageData(nullptr)
@@ -48,6 +48,21 @@ Decoder::~Decoder()
   MOZ_ASSERT(mInvalidRect.IsEmpty(),
              "Destroying Decoder without taking all its invalidations");
   mInitialized = false;
+
+  if (!NS_IsMainThread()) {
+    // Dispatch mImage to main thread to prevent it from being destructed by the
+    // decode thread.
+    nsCOMPtr<nsIThread> mainThread = do_GetMainThread();
+    NS_WARN_IF_FALSE(mainThread, "Couldn't get the main thread!");
+    if (mainThread) {
+      // Handle ambiguous nsISupports inheritance.
+      RasterImage* rawImg = nullptr;
+      mImage.swap(rawImg);
+      DebugOnly<nsresult> rv =
+        NS_ProxyRelease(mainThread, NS_ISUPPORTS_CAST(ImageResource*, rawImg));
+      MOZ_ASSERT(NS_SUCCEEDED(rv), "Failed to proxy release to main thread");
+    }
+  }
 }
 
 /*
@@ -181,13 +196,13 @@ Decoder::Finish(ShutdownReason aReason)
 
     if (consoleService && errorObject && !HasDecoderError()) {
       nsAutoString msg(NS_LITERAL_STRING("Image corrupt or truncated: ") +
-                       NS_ConvertUTF8toUTF16(mImage.GetURIString()));
+                       NS_ConvertUTF8toUTF16(mImage->GetURIString()));
 
       if (NS_SUCCEEDED(errorObject->InitWithWindowID(
                          msg,
-                         NS_ConvertUTF8toUTF16(mImage.GetURIString()),
+                         NS_ConvertUTF8toUTF16(mImage->GetURIString()),
                          EmptyString(), 0, 0, nsIScriptError::errorFlag,
-                         "Image", mImage.InnerWindowID()
+                         "Image", mImage->InnerWindowID()
                        ))) {
         consoleService->LogMessage(errorObject);
       }
@@ -218,11 +233,11 @@ Decoder::Finish(ShutdownReason aReason)
 
   // Set image metadata before calling DecodingComplete, because
   // DecodingComplete calls Optimize().
-  mImageMetadata.SetOnImage(&mImage);
+  mImageMetadata.SetOnImage(mImage);
 
   if (mDecodeDone) {
     MOZ_ASSERT(HasError() || mCurrentFrame, "Should have an error or a frame");
-    mImage.DecodingComplete(mCurrentFrame.get());
+    mImage->DecodingComplete(mCurrentFrame.get());
   }
 }
 
@@ -369,7 +384,7 @@ Decoder::InternalAddFrame(uint32_t aFrameNum,
   }
 
   InsertOutcome outcome =
-    SurfaceCache::Insert(frame, ImageKey(&mImage),
+    SurfaceCache::Insert(frame, ImageKey(mImage.get()),
                          RasterSurfaceKey(imageSize.ToIntSize(),
                                           aDecodeFlags,
                                           aFrameNum),
@@ -405,7 +420,7 @@ Decoder::InternalAddFrame(uint32_t aFrameNum,
   }
 
   mFrameCount++;
-  mImage.OnAddedFrame(mFrameCount, refreshArea);
+  mImage->OnAddedFrame(mFrameCount, refreshArea);
 
   return ref;
 }
@@ -416,9 +431,9 @@ Decoder::SetSizeOnImage()
   MOZ_ASSERT(mImageMetadata.HasSize(), "Should have size");
   MOZ_ASSERT(mImageMetadata.HasOrientation(), "Should have orientation");
 
-  mImage.SetSize(mImageMetadata.GetWidth(),
-                 mImageMetadata.GetHeight(),
-                 mImageMetadata.GetOrientation());
+  mImage->SetSize(mImageMetadata.GetWidth(),
+                  mImageMetadata.GetHeight(),
+                  mImageMetadata.GetOrientation());
 }
 
 /*
diff --git a/image/src/Decoder.h b/image/src/Decoder.h
index cc6d6134b759..7296faf1dbc3 100644
--- a/image/src/Decoder.h
+++ b/image/src/Decoder.h
@@ -22,7 +22,7 @@ class Decoder
 {
 public:
 
-  explicit Decoder(RasterImage& aImage);
+  explicit Decoder(RasterImage* aImage);
 
   /**
    * Initialize an image decoder. Decoders may not be re-initialized.
@@ -187,6 +187,11 @@ public:
 
   ImageMetadata& GetImageMetadata() { return mImageMetadata; }
 
+  /**
+   * Returns a weak pointer to the image associated with this decoder.
+   */
+  RasterImage* GetImage() const { MOZ_ASSERT(mImage); return mImage.get(); }
+
   // Tell the decoder infrastructure to allocate a frame. By default, frame 0
   // is created as an ARGB frame with no offset and with size width * height.
   // If decoders need something different, they must ask for it.
@@ -312,7 +317,7 @@ protected:
    * Member variables.
    *
    */
-  RasterImage &mImage;
+  nsRefPtr<RasterImage> mImage;
   RawAccessFrameRef mCurrentFrame;
   ImageMetadata mImageMetadata;
   nsIntRect mInvalidRect; // Tracks an invalidation region in the current frame.
diff --git a/image/src/RasterImage.cpp b/image/src/RasterImage.cpp
index f8dcea0c3287..cb73b848da73 100644
--- a/image/src/RasterImage.cpp
+++ b/image/src/RasterImage.cpp
@@ -1458,32 +1458,32 @@ RasterImage::InitDecoder(bool aDoSizeDecode)
   eDecoderType type = GetDecoderType(mSourceDataMimeType.get());
   CONTAINER_ENSURE_TRUE(type != eDecoderType_unknown, NS_IMAGELIB_ERROR_NO_DECODER);
 
-  // Instantiate the appropriate decoder
+  // Instantiate the appropriate decoder.
   switch (type) {
     case eDecoderType_png:
-      mDecoder = new nsPNGDecoder(*this);
+      mDecoder = new nsPNGDecoder(this);
       break;
     case eDecoderType_gif:
-      mDecoder = new nsGIFDecoder2(*this);
+      mDecoder = new nsGIFDecoder2(this);
       break;
     case eDecoderType_jpeg:
       // If we have all the data we don't want to waste cpu time doing
-      // a progressive decode
-      mDecoder = new nsJPEGDecoder(*this,
+      // a progressive decode.
+      mDecoder = new nsJPEGDecoder(this,
                                    mHasBeenDecoded ? Decoder::SEQUENTIAL :
                                                      Decoder::PROGRESSIVE);
       break;
     case eDecoderType_bmp:
-      mDecoder = new nsBMPDecoder(*this);
+      mDecoder = new nsBMPDecoder(this);
       break;
     case eDecoderType_ico:
-      mDecoder = new nsICODecoder(*this);
+      mDecoder = new nsICODecoder(this);
       break;
     case eDecoderType_icon:
-      mDecoder = new nsIconDecoder(*this);
+      mDecoder = new nsIconDecoder(this);
       break;
     default:
-      NS_ABORT_IF_FALSE(0, "Shouldn't get here!");
+      MOZ_ASSERT_UNREACHABLE("Unknown decoder type");
   }
 
   // Initialize the decoder