--- a/accessible/atk/AccessibleWrap.cpp
+++ b/accessible/atk/AccessibleWrap.cpp
@@ -1048,16 +1048,19 @@ GetInterfacesForProxy(ProxyAccessible* a
     interfaces |= MAI_INTERFACE_VALUE;
 
   if (aInterfaces & Interfaces::TABLE)
     interfaces |= MAI_INTERFACE_TABLE;
 
   if (aInterfaces & Interfaces::IMAGE)
     interfaces |= MAI_INTERFACE_IMAGE;
 
+  if (aInterfaces & Interfaces::DOCUMENT)
+    interfaces |= MAI_INTERFACE_DOCUMENT;
+
   return interfaces;
 }
 
 void
 a11y::ProxyCreated(ProxyAccessible* aProxy, uint32_t aInterfaces)
 {
   GType type = GetMaiAtkType(GetInterfacesForProxy(aProxy, aInterfaces));
   NS_ASSERTION(type, "why don't we have a type!");

--- a/accessible/ipc/DocAccessibleChild.cpp
+++ b/accessible/ipc/DocAccessibleChild.cpp
@@ -34,16 +34,19 @@ InterfacesFor(Accessible* aAcc)
     interfaces |= Interfaces::VALUE;
 
   if (aAcc->IsImage())
     interfaces |= Interfaces::IMAGE;
 
   if (aAcc->IsTableCell())
     interfaces |= Interfaces::TABLECELL;
 
+  if (aAcc->IsDoc())
+    interfaces |= Interfaces::DOCUMENT;
+
   return interfaces;
 }
 
 static void
 SerializeTree(Accessible* aRoot, nsTArray<AccessibleData>& aTree)
 {
   uint64_t id = reinterpret_cast<uint64_t>(aRoot->UniqueID());
   uint32_t role = aRoot->Role();

--- a/accessible/ipc/ProxyAccessible.h
+++ b/accessible/ipc/ProxyAccessible.h
@@ -315,14 +315,15 @@ private:
 enum Interfaces
 {
   HYPERTEXT = 1,
   HYPERLINK = 2,
   IMAGE = 4,
   VALUE = 8,
   TABLE = 16,
   TABLECELL = 32,
+  DOCUMENT = 64,
 };
 
 }
 }
 
 #endif