--- a/content/base/src/ImportManager.cpp
+++ b/content/base/src/ImportManager.cpp
@@ -737,32 +737,40 @@ ImportManager::AddLoaderWithNewURI(Impor
 }
 
 nsRefPtr<ImportLoader> ImportManager::GetNearestPredecessor(nsINode* aNode)
 {
   // Return the previous link if there is any in the same document.
   nsIDocument* doc = aNode->OwnerDoc();
   int32_t idx = doc->IndexOfSubImportLink(aNode);
   MOZ_ASSERT(idx != -1, "aNode must be a sub import link of its owner document");
+
+  for (; idx > 0; idx--) {
+    HTMLLinkElement* link =
+      static_cast<HTMLLinkElement*>(doc->GetSubImportLink(idx - 1));
+    nsCOMPtr<nsIURI> uri = link->GetHrefURI();
+    nsRefPtr<ImportLoader> ret;
+    mImports.Get(uri, getter_AddRefs(ret));
+    // Only main referrer links are interesting.
+    if (ret->GetMainReferrer() == link) {
+      return ret;
+    }
+  }
+
   if (idx == 0) {
     if (doc->IsMasterDocument()) {
       // If there is no previous one, and it was the master document, then
       // there is no predecessor.
       return nullptr;
     }
     // Else we find the main referrer of the import parent of the link's document.
     // And do a recursion.
     ImportLoader* owner = Find(doc);
     MOZ_ASSERT(owner);
     nsCOMPtr<nsINode> mainReferrer = owner->GetMainReferrer();
     return GetNearestPredecessor(mainReferrer);
   }
-  MOZ_ASSERT(idx > 0);
-  HTMLLinkElement* link =
-    static_cast<HTMLLinkElement*>(doc->GetSubImportLink(idx - 1));
-  nsCOMPtr<nsIURI> uri = link->GetHrefURI();
-  nsRefPtr<ImportLoader> ret;
-  mImports.Get(uri, getter_AddRefs(ret));
-  return ret;
+
+  return nullptr;
 }
 
 } // namespace dom
 } // namespace mozilla