diff --git a/mozilla/content/xul/document/src/nsXULDocument.cpp b/mozilla/content/xul/document/src/nsXULDocument.cpp
index 578dc277f02..38d19cc49d4 100644
--- a/mozilla/content/xul/document/src/nsXULDocument.cpp
+++ b/mozilla/content/xul/document/src/nsXULDocument.cpp
@@ -3673,6 +3673,7 @@ XULDocumentImpl::SetContentSink(nsIXULContentSink* aParentContentSink)
 NS_IMETHODIMP
 XULDocumentImpl::GetContentSink(nsIXULContentSink** aParentContentSink)
 {
+    NS_IF_ADDREF(mParentContentSink);
     *aParentContentSink = mParentContentSink;
     return NS_OK;
 }
diff --git a/mozilla/rdf/content/src/nsXULDocument.cpp b/mozilla/rdf/content/src/nsXULDocument.cpp
index 578dc277f02..38d19cc49d4 100644
--- a/mozilla/rdf/content/src/nsXULDocument.cpp
+++ b/mozilla/rdf/content/src/nsXULDocument.cpp
@@ -3673,6 +3673,7 @@ XULDocumentImpl::SetContentSink(nsIXULContentSink* aParentContentSink)
 NS_IMETHODIMP
 XULDocumentImpl::GetContentSink(nsIXULContentSink** aParentContentSink)
 {
+    NS_IF_ADDREF(mParentContentSink);
     *aParentContentSink = mParentContentSink;
     return NS_OK;
 }