diff --git a/lib/libmime/Makefile.in b/lib/libmime/Makefile.in
index 81c439dcf14d..5d7548abe558 100644
--- a/lib/libmime/Makefile.in
+++ b/lib/libmime/Makefile.in
@@ -80,7 +80,9 @@ ifndef MOZ_MAIL_COMPOSE
 DEFINES += -DMOZILLA_30
 endif
 
-DEFINES += -DNO_SECURITY
+ifdef MOZ_SECURITY
+DEFINES += -DMOZ_SECURITY
+endif
 
 #
 # Building the "mimefilt" executable, which reads a message from stdin and