diff --git a/mozilla/calendar/build.mk b/mozilla/calendar/build.mk
index 1042cd1e72e..e1eee717d01 100644
--- a/mozilla/calendar/build.mk
+++ b/mozilla/calendar/build.mk
@@ -36,6 +36,12 @@
 #
 # ***** END LICENSE BLOCK *****
 
+ifndef LIBXUL_SDK
+include $(topsrcdir)/toolkit/toolkit-tiers.mk
+endif
+
+TIERS += app
+
 ifdef MOZ_BRANDING_DIRECTORY
 tier_app_dirs += $(MOZ_BRANDING_DIRECTORY)
 endif