diff --git a/db/morkreader/nsMorkReader.h b/db/morkreader/nsMorkReader.h
index 130011be90a..1c5c3735aed 100644
--- a/db/morkreader/nsMorkReader.h
+++ b/db/morkreader/nsMorkReader.h
@@ -53,7 +53,7 @@
 //  http://www.mozilla.org/mailnews/arch/mork/grammar.txt
 //  http://www.jwz.org/hacks/mork.pl
 
-class nsMorkReader
+class NS_STACK_CLASS nsMorkReader
 {
  public:
   // This string type has built-in storage for the hex string representation