diff --git a/core/main.mk b/core/main.mk
index 4a2a626..0e058af 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -93,6 +93,9 @@
 # and host information.
 include $(BUILD_SYSTEM)/config.mk
 
+# CTS-specific config.
+-include cts/build/config.mk
+
 # This allows us to force a clean build - included after the config.mk
 # environment setup is done, but before we generate any dependencies.  This
 # file does the rm -rf inline so the deps which are all done below will