diff --git a/gfx/2d/DrawTargetD2D.cpp b/gfx/2d/DrawTargetD2D.cpp
index 28ec4893caed..077d7fb73d65 100644
--- a/gfx/2d/DrawTargetD2D.cpp
+++ b/gfx/2d/DrawTargetD2D.cpp
@@ -107,8 +107,10 @@ public:
       // We still need to take into account clipBounds if it contains additional
       // clipping information.
       RefPtr<ID2D1RectangleGeometry> rectGeom;
-      factory()->CreateRectangleGeometry(D2D1::Rect(clipBounds.x, clipBounds.y,
-                                                    clipBounds.XMost(), clipBounds.YMost()),
+      factory()->CreateRectangleGeometry(D2D1::Rect(Float(clipBounds.x),
+                                                    Float(clipBounds.y),
+                                                    Float(clipBounds.XMost()),
+                                                    Float(clipBounds.YMost())),
                                          byRef(rectGeom));
 
       mClippedArea = mDT->Intersect(mClippedArea, rectGeom);
diff --git a/gfx/2d/RecordedEvent.cpp b/gfx/2d/RecordedEvent.cpp
index b7b6c6d69af0..c8b649b93098 100644
--- a/gfx/2d/RecordedEvent.cpp
+++ b/gfx/2d/RecordedEvent.cpp
@@ -211,7 +211,9 @@ RecordedEvent::ReadStrokeOptions(std::istream &aStream, StrokeOptions &aStrokeOp
   ReadElement(aStream, aStrokeOptions.mMiterLimit);
   ReadElement(aStream, joinStyle);
   ReadElement(aStream, capStyle);
-  aStrokeOptions.mDashLength = dashLength;
+  // On 32 bit we truncate the value of dashLength.
+  // See also bug 811850 for history.
+  aStrokeOptions.mDashLength = size_t(dashLength);
   aStrokeOptions.mLineJoin = joinStyle;
   aStrokeOptions.mLineCap = capStyle;
 
diff --git a/gfx/2d/SourceSurfaceD2D.cpp b/gfx/2d/SourceSurfaceD2D.cpp
index 3f388e463296..c6ff601aa2d1 100644
--- a/gfx/2d/SourceSurfaceD2D.cpp
+++ b/gfx/2d/SourceSurfaceD2D.cpp
@@ -171,7 +171,9 @@ DataSourceSurfaceD2D::DataSourceSurfaceD2D(SourceSurfaceD2D* aSourceSurface)
 
   renderTarget->BeginDraw();
   renderTarget->DrawBitmap(aSourceSurface->mBitmap,
-                           D2D1::RectF(0, 0, mSize.width, mSize.height));
+                           D2D1::RectF(0, 0,
+                                       Float(mSize.width),
+                                       Float(mSize.height)));
   renderTarget->EndDraw();
 
   desc.CPUAccessFlags = D3D10_CPU_ACCESS_READ;