diff --git a/mailnews/ui/messenger/src/Makefile.in b/mailnews/ui/messenger/src/Makefile.in
index a5678736cdf..79b3bf82a88 100644
--- a/mailnews/ui/messenger/src/Makefile.in
+++ b/mailnews/ui/messenger/src/Makefile.in
@@ -29,6 +29,10 @@ CPPSRCS =	\
 	nsMsgAppCore.cpp	\
 	$(NULL)
 
+EXPORTS =	\
+	nsMsgAppCore.h	\
+	$(NULL)
+
 include $(topsrcdir)/config/config.mk
 
 include $(topsrcdir)/config/rules.mk