diff --git a/layout/base/RestyleManager.cpp b/layout/base/RestyleManager.cpp
index 11b72323f1a0..b2431378167e 100644
--- a/layout/base/RestyleManager.cpp
+++ b/layout/base/RestyleManager.cpp
@@ -148,7 +148,8 @@ SyncViewsAndInvalidateDescendants(nsIFrame* aFrame,
 {
   NS_PRECONDITION(gInApplyRenderingChangeToTree,
                   "should only be called within ApplyRenderingChangeToTree");
-  NS_ASSERTION(aChange == (aChange & (nsChangeHint_RepaintFrame |
+  NS_ASSERTION(nsChangeHint_size_t(aChange) ==
+                          (aChange & (nsChangeHint_RepaintFrame |
                                       nsChangeHint_SyncFrameView |
                                       nsChangeHint_UpdateOpacityLayer |
                                       nsChangeHint_SchedulePaint)),
diff --git a/layout/base/nsChangeHint.h b/layout/base/nsChangeHint.h
index edc497ce13a8..8be945cb72b0 100644
--- a/layout/base/nsChangeHint.h
+++ b/layout/base/nsChangeHint.h
@@ -210,6 +210,49 @@ inline bool NS_IsHintSubset(nsChangeHint aSubset, nsChangeHint aSuperSet) {
   return (aSubset & aSuperSet) == aSubset;
 }
 
+// The functions below need an integral type to cast to to avoid
+// infinite recursion.
+typedef decltype(nsChangeHint(0) + nsChangeHint(0)) nsChangeHint_size_t;
+
+inline nsChangeHint MOZ_CONSTEXPR
+operator|(nsChangeHint aLeft, nsChangeHint aRight)
+{
+  return nsChangeHint(nsChangeHint_size_t(aLeft) | nsChangeHint_size_t(aRight));
+}
+
+inline nsChangeHint MOZ_CONSTEXPR
+operator&(nsChangeHint aLeft, nsChangeHint aRight)
+{
+  return nsChangeHint(nsChangeHint_size_t(aLeft) & nsChangeHint_size_t(aRight));
+}
+
+inline nsChangeHint& operator|=(nsChangeHint& aLeft, nsChangeHint aRight)
+{
+  return aLeft = aLeft | aRight;
+}
+
+inline nsChangeHint& operator&=(nsChangeHint& aLeft, nsChangeHint aRight)
+{
+  return aLeft = aLeft & aRight;
+}
+
+inline nsChangeHint MOZ_CONSTEXPR
+operator~(nsChangeHint aArg)
+{
+  return nsChangeHint(~nsChangeHint_size_t(aArg));
+}
+
+inline nsChangeHint MOZ_CONSTEXPR
+operator^(nsChangeHint aLeft, nsChangeHint aRight)
+{
+  return nsChangeHint(nsChangeHint_size_t(aLeft) ^ nsChangeHint_size_t(aRight));
+}
+
+inline nsChangeHint operator^=(nsChangeHint& aLeft, nsChangeHint aRight)
+{
+  return aLeft = aLeft ^ aRight;
+}
+
 /**
  * We have an optimization when processing change hints which prevents
  * us from visiting the descendants of a node when a hint on that node