--- a/layout/style/nsCSSValue.cpp
+++ b/layout/style/nsCSSValue.cpp
@@ -2843,16 +2843,37 @@ css::URLValueData::GetURI() const
               nullptr, const_cast<nsIURI*>(mBaseURI.get()));
     mURI = new PtrHolder<nsIURI>(newURI.forget());
     mURIResolved = true;
   }
 
   return mURI;
 }
 
+bool
+css::URLValueData::HasRef() const
+{
+  if (IsLocalRef()) {
+    return true;
+  }
+
+  nsIURI* uri = GetURI();
+  if (!uri) {
+    return false;
+  }
+
+  nsAutoCString ref;
+  nsresult rv = uri->GetRef(ref);
+  if (NS_SUCCEEDED(rv) && !ref.IsEmpty()) {
+    return true;
+  }
+
+  return false;
+}
+
 already_AddRefed<nsIURI>
 css::URLValueData::ResolveLocalRef(nsIURI* aURI) const
 {
   nsCOMPtr<nsIURI> result = GetURI();
 
   if (result && mIsLocalRef) {
     nsCString ref;
     mURI->GetRef(ref);

--- a/layout/style/nsCSSValue.h
+++ b/layout/style/nsCSSValue.h
@@ -133,16 +133,18 @@ public:
   // Smae as DefinitelyEqualURIs but additionally compares the nsIPrincipal
   // pointers of the two URLValueData objects.
   bool DefinitelyEqualURIsAndPrincipal(const URLValueData& aOther) const;
 
   nsIURI* GetURI() const;
 
   bool IsLocalRef() const { return mIsLocalRef; }
 
+  bool HasRef() const;
+
   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(URLValueData)
 
   // When matching a url with mIsLocalRef set, resolve it against aURI;
   // Otherwise, ignore aURL and return mURL directly.
   already_AddRefed<nsIURI> ResolveLocalRef(nsIURI* aURI) const;
   already_AddRefed<nsIURI> ResolveLocalRef(nsIContent* aContent) const;
 
   // Serializes mURI as a computed URI value, taking into account mIsLocalRef

--- a/layout/style/nsStyleStruct.cpp
+++ b/layout/style/nsStyleStruct.cpp
@@ -2927,31 +2927,21 @@ nsStyleImageLayers::Layer::CalcDifferenc
     //   mask:url(#localMaskID); // The fragment of this URI is an ID of a mask
     //                           // element in local document.
     //   mask:url(b.svg#viewBoxID); // The fragment of this URI is an ID of a
     //                              // viewbox defined in b.svg.
     // That is, if mSourceURI has a fragment, it may link to a SVG mask; If
     // not, it "must" not link to a SVG mask.
     bool maybeSVGMask = false;
     if (mSourceURI) {
-      if (mSourceURI->IsLocalRef()) {
-        maybeSVGMask = true;
-      } else if (mSourceURI->GetURI()) {
-        mSourceURI->GetURI()->GetHasRef(&maybeSVGMask);
-      }
+      maybeSVGMask = mSourceURI->HasRef();
     }
 
-    if (!maybeSVGMask) {
-      if (aNewLayer.mSourceURI) {
-        if (aNewLayer.mSourceURI->IsLocalRef()) {
-          maybeSVGMask = true;
-        } else if (aNewLayer.mSourceURI->GetURI()) {
-          aNewLayer.mSourceURI->GetURI()->GetHasRef(&maybeSVGMask);
-        }
-      }
+    if (!maybeSVGMask && aNewLayer.mSourceURI) {
+      maybeSVGMask = aNewLayer.mSourceURI->HasRef();
     }
 
     // Return nsChangeHint_UpdateOverflow if either URI might link to an SVG
     // mask.
     if (maybeSVGMask) {
       // Mask changes require that we update the PreEffectsBBoxProperty,
       // which is done during overflow computation.
       hint |= nsChangeHint_UpdateOverflow;