diff --git a/Makefile b/Makefile
index f8303e1376..bf04773d26 100644
--- a/Makefile
+++ b/Makefile
@@ -441,6 +441,7 @@ external-deps:
 		SPIDER=--spider source
 
 ifeq ($(BR2_CONFIG_CACHE),y)
+# drop configure cache if configuration is changed
 $(BUILD_DIR)/tgt-config.cache: .config
 	rm -f $@
 	touch $@