diff --git a/gfx/2d/DrawTargetCG.cpp b/gfx/2d/DrawTargetCG.cpp
index 100d0055d3d..65eee44199f 100644
--- a/gfx/2d/DrawTargetCG.cpp
+++ b/gfx/2d/DrawTargetCG.cpp
@@ -152,7 +152,6 @@ DrawTargetCG::~DrawTargetCG()
     CGColorSpaceRelease(mColorSpace);
   if (mCg)
     CGContextRelease(mCg);
-  free(mData);
 }
 
 BackendType
@@ -1188,7 +1187,6 @@ DrawTargetCG::Init(BackendType aType,
       aSize.width > 32767 || aSize.height > 32767) {
     mColorSpace = nullptr;
     mCg = nullptr;
-    mData = nullptr;
     return false;
   }
 
@@ -1199,12 +1197,9 @@ DrawTargetCG::Init(BackendType aType,
 
   if (aData == nullptr && aType != BACKEND_COREGRAPHICS_ACCELERATED) {
     // XXX: Currently, Init implicitly clears, that can often be a waste of time
-    mData = calloc(aSize.height * aStride, 1);
-    aData = static_cast<unsigned char*>(mData);  
-  } else {
-    // mData == nullptr means DrawTargetCG doesn't own the image data and will not
-    // delete it in the destructor
-    mData = nullptr;
+    mData.Realloc(aStride * aSize.height);
+    aData = static_cast<unsigned char*>(mData);
+    memset(aData, 0, aStride * aSize.height);
   }
 
   mSize = aSize;
@@ -1214,7 +1209,6 @@ DrawTargetCG::Init(BackendType aType,
     mCg = ioSurface->CreateIOSurfaceContext();
     // If we don't have the symbol for 'CreateIOSurfaceContext' mCg will be null
     // and we will fallback to software below
-    mData = nullptr;
   }
 
   mFormat = FORMAT_B8G8R8A8;
@@ -1287,7 +1281,6 @@ DrawTargetCG::Init(CGContextRef cgContext, const IntSize &aSize)
   if (aSize.width == 0 || aSize.height == 0) {
     mColorSpace = nullptr;
     mCg = nullptr;
-    mData = nullptr;
     return false;
   }
 
@@ -1301,8 +1294,6 @@ DrawTargetCG::Init(CGContextRef cgContext, const IntSize &aSize)
   mCg = cgContext;
   CGContextRetain(mCg);
 
-  mData = nullptr;
-
   assert(mCg);
 
   // CGContext's default to have the origin at the bottom left.
@@ -1331,7 +1322,7 @@ DrawTargetCG::Init(CGContextRef cgContext, const IntSize &aSize)
 bool
 DrawTargetCG::Init(BackendType aType, const IntSize &aSize, SurfaceFormat &aFormat)
 {
-  int stride = aSize.width*4;
+  int32_t stride = GetAlignedStride<16>(aSize.width * BytesPerPixel(aFormat));
   
   // Calling Init with aData == nullptr will allocate.
   return Init(aType, nullptr, aSize, stride, aFormat);
diff --git a/gfx/2d/DrawTargetCG.h b/gfx/2d/DrawTargetCG.h
index d2edc3669fb..7b21930983c 100644
--- a/gfx/2d/DrawTargetCG.h
+++ b/gfx/2d/DrawTargetCG.h
@@ -10,6 +10,7 @@
 #include "PathCG.h"
 #include "SourceSurfaceCG.h"
 #include "GLDefs.h"
+#include "Tools.h"
 
 namespace mozilla {
 namespace gfx {
@@ -157,14 +158,12 @@ private:
   CGContextRef mCg;
 
   /**
-   * A pointer to the image buffer if the buffer is owned by this class (set to
-   * nullptr otherwise).
-   * The data is not considered owned by DrawTargetCG if the DrawTarget was 
-   * created for a pre-existing buffer or if the buffer's lifetime is managed
-   * by CoreGraphics.
-   * Data owned by DrawTargetCG will be deallocated in the destructor. 
+   * The image buffer, if the buffer is owned by this class.
+   * If the DrawTarget was created for a pre-existing buffer or if the buffer's
+   * lifetime is managed by CoreGraphics, mData will be null.
+   * Data owned by DrawTargetCG will be deallocated in the destructor.
    */
-  void *mData;
+  AlignedArray<uint8_t> mData;
 
   RefPtr<SourceSurfaceCGContext> mSnapshot;
 };