diff --git a/layout/base/src/nsSelection.h b/layout/base/src/nsSelection.h
index 056ab11a0071..036509331e32 100644
--- a/layout/base/src/nsSelection.h
+++ b/layout/base/src/nsSelection.h
@@ -59,4 +59,7 @@ class nsSelection : public nsISelection {
     char * ToString();
 };
 
+extern NS_LAYOUT nsresult
+  NS_NewSelection(nsISelection** aInstancePtrResult);
+
 #endif /* nsSelection_h___ */