diff --git a/apk_filter_installed.sh b/apk_filter_installed.sh
index 0d5fc2c7..caa21892 100755
--- a/apk_filter_installed.sh
+++ b/apk_filter_installed.sh
@@ -13,7 +13,7 @@
 #  https://www.linkedin.com/in/harisekhon
 #
 
-set -euo pipefail
+set -eu  #o pipefail  # not available in POSIX sh
 [ -n "${DEBUG:-}" ] && set -x
 srcdir="$(dirname "$0")"