diff --git a/package/cjson/cjson.mk b/package/cjson/cjson.mk
index aabf3677ea..6dff7d6567 100644
--- a/package/cjson/cjson.mk
+++ b/package/cjson/cjson.mk
@@ -15,6 +15,9 @@ CJSON_CONF_OPTS += \
 	-DENABLE_CJSON_TEST=OFF \
 	-DENABLE_CUSTOM_COMPILER_FLAGS=OFF
 
+# If BUILD_SHARED_AND_STATIC_LIBS is set to OFF, cjson uses the
+# standard BUILD_SHARED_LIBS option which is passed by the
+# cmake-package infrastructure.
 ifeq ($(BR2_SHARED_STATIC_LIBS),y)
 CJSON_CONF_OPTS += -DBUILD_SHARED_AND_STATIC_LIBS=ON
 else