diff --git a/build/libraries/Makefile b/build/libraries/Makefile
index 36a963d0..f316ea53 100644
--- a/build/libraries/Makefile
+++ b/build/libraries/Makefile
@@ -23,7 +23,7 @@ include	$(TWL_IPL_RED_ROOT)/build/buildtools/commondefs
 
 SUBDIRS_P	= \
 			init \
-#			os \
+			os \
 			pxi \
 			fs \
 			mi \