diff --git a/rdf/base/src/nsInMemoryDataSource.cpp b/rdf/base/src/nsInMemoryDataSource.cpp
index 42189a38a3ed..b711778626a6 100644
--- a/rdf/base/src/nsInMemoryDataSource.cpp
+++ b/rdf/base/src/nsInMemoryDataSource.cpp
@@ -1758,6 +1758,8 @@ InMemoryDataSource::ResourceEnumerator(PLDHashTable* aTable,
 NS_IMETHODIMP
 InMemoryDataSource::GetAllResources(nsISimpleEnumerator** aResult)
 {
+    nsresult rv;
+
     nsCOMArray<nsIRDFNode> nodes;
     if (!nodes.SetCapacity(mForwardArcs.entryCount)) {
       return NS_ERROR_OUT_OF_MEMORY;