diff --git a/layout/base/nsCSSFrameConstructor.cpp b/layout/base/nsCSSFrameConstructor.cpp
index 788e03c8f1e3..f9aaf8d9f162 100644
--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -4875,6 +4875,7 @@ nsCSSFrameConstructor::ConstructFrameByTag(nsIPresShell*            aPresShell,
         if (!aState.mPseudoFrames.IsEmpty()) { // process pending pseudo frames
           ProcessPseudoFrames(aPresContext, aState.mPseudoFrames, aFrameItems); 
         }
+        isReplaced = PR_TRUE;
         rv = NS_NewObjectFrame(aPresShell, &newFrame);
       }
       else if (nsHTMLAtoms::fieldset == aTag) {
diff --git a/layout/html/style/src/nsCSSFrameConstructor.cpp b/layout/html/style/src/nsCSSFrameConstructor.cpp
index 788e03c8f1e3..f9aaf8d9f162 100644
--- a/layout/html/style/src/nsCSSFrameConstructor.cpp
+++ b/layout/html/style/src/nsCSSFrameConstructor.cpp
@@ -4875,6 +4875,7 @@ nsCSSFrameConstructor::ConstructFrameByTag(nsIPresShell*            aPresShell,
         if (!aState.mPseudoFrames.IsEmpty()) { // process pending pseudo frames
           ProcessPseudoFrames(aPresContext, aState.mPseudoFrames, aFrameItems); 
         }
+        isReplaced = PR_TRUE;
         rv = NS_NewObjectFrame(aPresShell, &newFrame);
       }
       else if (nsHTMLAtoms::fieldset == aTag) {