diff --git a/build/check_embedded.pl b/build/check_embedded.pl
index f356636c..db73b0f7 100755
--- a/build/check_embedded.pl
+++ b/build/check_embedded.pl
@@ -53,7 +53,7 @@
 #
 # Load expiry whitelist.
 #
-open WL, '../build/expiry_whitelist.txt' || die "can't open certificate expiry whitelist";
+open(WL, '../build/expiry_whitelist.txt') || die "can't open certificate expiry whitelist";
 while (<WL>) {
 	# fold lines
 	while (/^(.*)\\\s*$/) {