diff --git a/dnsapi/dns_ali.sh b/dnsapi/dns_ali.sh
index 90196c69..62e54e0c 100755
--- a/dnsapi/dns_ali.sh
+++ b/dnsapi/dns_ali.sh
@@ -69,8 +69,8 @@ _ali_rest() {
   ign="$2"
   mtd="${3:-GET}"
 
-  signature=$(printf "%s" "$mtd&%2F&$(printf "%s" "$query" | _url_encode upper-hex)" | _hmac "sha1" "$(printf "%s" "$Ali_Secret&" | _hex_dump | tr -d " ")" | _base64)
-  signature=$(printf "%s" "$signature" | _url_encode upper-hex)
+  signature=$(printf "%s" "$mtd&%2F&$(printf "%s" "$query" | _ali_urlencode_upper)" | _hmac "sha1" "$(printf "%s" "$Ali_Secret&" | _hex_dump | tr -d " ")" | _base64)
+  signature=$(printf "%s" "$signature" | _ali_urlencode_upper)
   url="$endpoint?Signature=$signature"
 
   if [ "$mtd" = "GET" ]; then
@@ -96,6 +96,20 @@ _ali_rest() {
   fi
 }
 
+# stdin stdout
+# The Aliyun signature requires percent-encoding with upper-case hex.
+# Do not use "_url_encode upper-hex" here: this file is also bundled by
+# third parties (e.g. Proxmox VE proxmox-acme) whose older copies of the
+# acme.sh function library ignore the upper-hex argument and output
+# lower-case hex, which invalidates the signature.
+# https://github.com/acmesh-official/acme.sh/issues/6272
+_ali_urlencode_upper() {
+  {
+    _url_encode
+    echo
+  } | sed 's/%a/%A/g;s/%b/%B/g;s/%c/%C/g;s/%d/%D/g;s/%e/%E/g;s/%f/%F/g;s/%\(.\)a/%\1A/g;s/%\(.\)b/%\1B/g;s/%\(.\)c/%\1C/g;s/%\(.\)d/%\1D/g;s/%\(.\)e/%\1E/g;s/%\(.\)f/%\1F/g'
+}
+
 _ali_nonce() {
   if [ "$ACME_OPENSSL_BIN" ]; then
     "$ACME_OPENSSL_BIN" rand -hex 16 2>/dev/null && return 0