diff --git a/mozilla/rdf/base/src/nsInMemoryDataSource.cpp b/mozilla/rdf/base/src/nsInMemoryDataSource.cpp
index 5d1d1b8ceca..c316fc66e9c 100644
--- a/mozilla/rdf/base/src/nsInMemoryDataSource.cpp
+++ b/mozilla/rdf/base/src/nsInMemoryDataSource.cpp
@@ -1432,6 +1432,7 @@ InMemoryDataSource::DoCommand(const char* aCommand,
 
 ////////////////////////////////////////////////////////////////////////
 
+nsresult NS_NewRDFInMemoryDataSource(nsIRDFDataSource** result);
 nsresult
 NS_NewRDFInMemoryDataSource(nsIRDFDataSource** result)
 {