diff --git a/layout/html/forms/src/nsFormFrame.cpp b/layout/html/forms/src/nsFormFrame.cpp
index 35c716991a35..fb05791565db 100644
--- a/layout/html/forms/src/nsFormFrame.cpp
+++ b/layout/html/forms/src/nsFormFrame.cpp
@@ -50,6 +50,7 @@
 #include "nsIPresShell.h"
 #include "nsIPresContext.h"
 #include "nsIStyleContext.h"
+#include "nsIMutableStyleContext.h"
 #include "nsCSSRendering.h"
 #include "nsHTMLIIDs.h"
 #include "nsDebug.h"
@@ -166,6 +167,16 @@ nsFormFrame::~nsFormFrame()
   }
 }
 
+NS_METHOD nsFormFrame::DidSetStyleContext(nsIPresContext* aPresContext)
+{
+  // we can't yet support anything but display:block on a form, 
+  // so make sure that the display is block
+  nsMutableStyleDisplay displayData(mStyleContext);
+  displayData->mDisplay = NS_STYLE_DISPLAY_BLOCK;
+
+  return NS_OK;
+}
+
 PRBool 
 nsFormFrame::CanSubmit(nsIFormControlFrame *aFrame)
 { 
diff --git a/layout/html/forms/src/nsFormFrame.h b/layout/html/forms/src/nsFormFrame.h
index 99181a2f28cc..66c941f399be 100644
--- a/layout/html/forms/src/nsFormFrame.h
+++ b/layout/html/forms/src/nsFormFrame.h
@@ -102,6 +102,7 @@ public:
 protected:
   NS_IMETHOD_(nsrefcnt) AddRef(void);
   NS_IMETHOD_(nsrefcnt) Release(void);
+  NS_IMETHOD DidSetStyleContext(nsIPresContext* aPresContext);
   void RemoveRadioGroups();
 
   void DoDefaultSelection(nsIPresContext*          aPresContext,