diff --git a/ofw/build.sh b/ofw/build.sh
index 71ddb7b..68a5bcc 100755
--- a/ofw/build.sh
+++ b/ofw/build.sh
@@ -5,10 +5,9 @@ mkdir -p out
 cpp -w -nostdinc -traditional-cpp -undef -P -C -I. of.fs > out/of-blob.tmp
 sed -e 's/^[	 ]*//' < out/of-blob.tmp \
   | sed -e '/^\\[	 ]/d' \
-  | sed -e '/^([	 ][^)]*[	 ])[	 ]*$$/d' \
-  | sed -e '/^$$/d' \
-  | cat -s > out/of-blob.fs
+  | sed -e 's/[	 ]\\[	 ].+$//' \
+  | sed -e '/^([	 ][^)]*[	 ])[	 ]*$/d' \
+  | sed -e '/^$/d' > out/of-blob.fs
 
 rm -f out/of-blob.tmp
 
-