--- a/dom/base/nsObjectLoadingContent.cpp
+++ b/dom/base/nsObjectLoadingContent.cpp
@@ -3428,16 +3428,24 @@ nsObjectLoadingContent::HasGoodFallback(
            child;
            child = child->GetNextNode(thisContent)) {
         if (child->IsHTMLElement(nsGkAtoms::video)) {
           return true;
         }
       }
     }
 
+    // RULE "nosrc":
+    // Use fallback content if the object has not specified an URI.
+    if (rulesList[i].EqualsLiteral("nosrc")) {
+      if (!mOriginalURI) {
+        return true;
+      }
+    }
+
     // RULE "adobelink":
     // Don't use fallback content when it has a link to adobe's website.
     if (rulesList[i].EqualsLiteral("adobelink")) {
       nsTArray<nsINodeList*> childNodes;
       for (nsIContent* child = thisContent->GetFirstChild();
            child;
            child = child->GetNextNode(thisContent)) {
         if (child->IsHTMLElement(nsGkAtoms::a)) {