--- a/layout/style/ServoBindings.toml
+++ b/layout/style/ServoBindings.toml
@@ -269,16 +269,17 @@ opaque-types = [
     "SupportsWeakPtr",
     "mozilla::detail::WeakReference",
     "mozilla::WeakPtr",
     "nsWritingIterator_reference", "nsReadingIterator_reference",
     "nsTObserverArray",  # <- Inherits from nsAutoTObserverArray<T, 0>
     "nsTHashtable",  # <- Inheriting from inner typedefs that clang
                      #    doesn't expose properly.
     "nsRefPtrHashtable", "nsDataHashtable", "nsClassHashtable",  # <- Ditto
+    "nsInterfaceHashtable",  # <- Ditto
     "nsIDocument_SelectorCache",  # <- Inherits from nsExpirationTracker<.., 4>
     "nsIPresShell_ScrollAxis",  # <- For some reason the alignment of this is 4
                                 # for clang.
     "nsPIDOMWindow",  # <- Takes the vtable from a template parameter, and we can't
                       #    generate it conditionally.
     "JS::Rooted",
     "mozilla::Maybe",
     "gfxSize",  # <- union { struct { T width; T height; }; T components[2] };