diff --git a/layout/generic/nsBlockFrame.cpp b/layout/generic/nsBlockFrame.cpp
index 2f23c9b2336a..9f993e4ac15c 100644
--- a/layout/generic/nsBlockFrame.cpp
+++ b/layout/generic/nsBlockFrame.cpp
@@ -6645,8 +6645,19 @@ nsBlockFrame::Init(nsIContent*       aContent,
   nsBlockFrameSuper::Init(aContent, aParent, aPrevInFlow);
 
   if (!aPrevInFlow ||
-      aPrevInFlow->GetStateBits() & NS_BLOCK_NEEDS_BIDI_RESOLUTION)
+      aPrevInFlow->GetStateBits() & NS_BLOCK_NEEDS_BIDI_RESOLUTION) {
     AddStateBits(NS_BLOCK_NEEDS_BIDI_RESOLUTION);
+  }
+
+  // If a box has a different block flow direction than its containing block:
+  // ...
+  //   If the box is a block container, then it establishes a new block
+  //   formatting context.
+  // (http://dev.w3.org/csswg/css-writing-modes/#block-flow)
+  if (GetParent() && StyleVisibility()->mWritingMode !=
+                     GetParent()->StyleVisibility()->mWritingMode) {
+    AddStateBits(NS_BLOCK_FLOAT_MGR | NS_BLOCK_MARGIN_ROOT);
+  }
 
   if ((GetStateBits() &
        (NS_FRAME_FONT_INFLATION_CONTAINER | NS_BLOCK_FLOAT_MGR)) ==