diff --git a/Makefile b/Makefile
index 98e42fc..92203c5 100644
--- a/Makefile
+++ b/Makefile
@@ -47,7 +47,7 @@ ifdef PLATFORM_DIR
     platform_parent_dir=$(platform_dir_path)
   else
     PLATFORM=$(shell basename $(platform_dir_path))
-    platform_parent_dir=$(subst $(PLATFORM),,$(platform_dir_path))
+    platform_parent_dir=$(shell realpath ${platform_dir_path}/..)
   endif
 else
  platform_parent_dir=$(src_dir)/platform