--- a/layout/style/nsCSSValue.cpp
+++ b/layout/style/nsCSSValue.cpp
@@ -2713,21 +2713,23 @@ css::URLValueData::DefinitelyEqualURIsAn
 nsIURI*
 css::URLValueData::GetURI() const
 {
   MOZ_ASSERT(NS_IsMainThread());
 
   if (!mURIResolved) {
     MOZ_ASSERT(!mURI);
     nsCOMPtr<nsIURI> newURI;
-    NS_NewURI(getter_AddRefs(newURI),
-              NS_ConvertUTF16toUTF8(nsCSSValue::GetBufferValue(mString)),
-              nullptr, const_cast<nsIURI*>(mBaseURI.get()));
-    mURI = new PtrHolder<nsIURI>(newURI.forget());
-    mURIResolved = true;
+    if (NS_ConvertUTF16toUTF8(nsCSSValue::GetBufferValue(mString)) != "") {
+      NS_NewURI(getter_AddRefs(newURI),
+                NS_ConvertUTF16toUTF8(nsCSSValue::GetBufferValue(mString)),
+                nullptr, const_cast<nsIURI*>(mBaseURI.get()));
+      mURI = new PtrHolder<nsIURI>(newURI.forget());
+      mURIResolved = true;
+    }
   }
 
   return mURI;
 }
 
 already_AddRefed<nsIURI>
 css::URLValueData::ResolveLocalRef(nsIURI* aURI) const
 {