diff --git a/pgmoon/init.lua b/pgmoon/init.lua
index e42d642..1caa194 100644
--- a/pgmoon/init.lua
+++ b/pgmoon/init.lua
@@ -401,14 +401,14 @@ do
               local server_cert = self.sock:getpeercertificate()
               pem, signature = server_cert:pem(), server_cert:getsignaturename()
             end
-            signature = signature:lower()
-            local _, with_sig
-            _, _, with_sig = signature:find("%-with%-(.*)")
-            if with_sig then
-              signature = with_sig
-            end
-            if signature:match("^md5") or signature:match("^sha1") or signature:match("sha1$") then
+            local sig_lower = signature:lower()
+            if sig_lower:match("^md5") or sig_lower:match("^sha1") or sig_lower:match("sha1$") or sig_lower:match("sha256$") then
               signature = "sha256"
+            else
+              local objects = require("resty.openssl.objects")
+              local sigid = assert(objects.txt2nid(signature))
+              local digest_nid = assert(objects.find_sigid_algs(sigid))
+              signature = assert(objects.nid2table(digest_nid).sn)
             end
             cbind_data = assert(x509_digest(pem, signature))
           end
diff --git a/pgmoon/init.moon b/pgmoon/init.moon
index 7844393..20a27d0 100644
--- a/pgmoon/init.moon
+++ b/pgmoon/init.moon
@@ -404,16 +404,16 @@ class Postgres
             server_cert = @sock\getpeercertificate()
             server_cert\pem!, server_cert\getsignaturename!
 
-          signature = signature\lower!
-
-          -- Handle the case when the signature is e.g. ECDSA-with-SHA384
-          _, _, with_sig = signature\find("%-with%-(.*)")
-          if with_sig
-            signature = with_sig
+          sig_lower = signature\lower!
 
           -- upgrade the signature if necessary (also handle the case of s/RSA-SHA1/sha256)
-          if signature\match("^md5") or signature\match("^sha1") or signature\match("sha1$")
+          if sig_lower\match("^md5") or sig_lower\match("^sha1") or sig_lower\match("sha1$") or sig_lower\match("sha256$")
             signature = "sha256"
+          else
+            objects = require "resty.openssl.objects"
+            sigid = assert objects.txt2nid(signature)
+            digest_nid = assert objects.find_sigid_algs(sigid)
+            signature = assert objects.nid2table(digest_nid).sn
 
           assert x509_digest(pem, signature)