diff --git a/src/test/check-missing-functions b/src/test/check-missing-functions
index c8a2b3d..cb819fc 100755
--- a/src/test/check-missing-functions
+++ b/src/test/check-missing-functions
@@ -10,5 +10,5 @@ PRESENT=$(awk 'BEGIN{ORS="|";} /^_/{ gsub(/\(\) {/, ""); print $0}' \
 LOCAL=$(awk 'BEGIN{ORS="|";} /^_/{ gsub(/\(\) {/, ""); print $0}' \
 	../acme.sh/dnsapi/dns*.sh | sed -r 's/\|$//')
 
-grep -P '\b_[a-zA-Z0-9_-]+ ' ../acme.sh/dnsapi/dns_*sh | \
+grep -P '(?<!["$])\b_[a-zA-Z0-9_-]+ ' ../acme.sh/dnsapi/dns_*sh | \
 	grep -Ev "$PRESENT|$LOCAL|\b_[a-zA-Z0-9_-]+=|^../acme.sh/dnsapi/.*sh: *#"