diff --git a/core/Makefile b/core/Makefile
index 82cd784..9e001f3 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1064,6 +1064,9 @@
 ifdef mkyaffs2_extra_flags
 	$(hide) echo "mkyaffs2_extra_flags=$(mkyaffs2_extra_flags)" >> $(zip_root)/META/misc_info.txt
 endif
+ifdef INTERNAL_USERIMAGES_SPARSE_EXT_FLAG
+	$(hide) echo "extfs_sparse_flag=$(INTERNAL_USERIMAGES_SPARSE_EXT_FLAG)" >> $(zip_root)/META/misc_info.txt
+endif
 	@# Zip everything up, preserving symlinks
 	$(hide) (cd $(zip_root) && zip -qry ../$(notdir $@) .)
 	@# Run fs_config on all the system files in the zip, and save the output