diff --git a/core/main.mk b/core/main.mk
index 1975bdb5d..a616875bf 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -438,6 +438,7 @@ subdirs += \
 	sdk/layoutlib_api \
 	sdk/layoutopt \
 	sdk/ninepatch \
+	sdk/rule_api \
 	sdk/sdkstats \
 	sdk/sdkmanager \
 	sdk/swtmenubar \