diff --git a/pgx/src/io_intf.ml b/pgx/src/io_intf.ml
index e6c55c0..1b1a870 100644
--- a/pgx/src/io_intf.ml
+++ b/pgx/src/io_intf.ml
@@ -14,7 +14,7 @@ module type S = sig
     | Inet of string * int
 
   val open_connection : sockaddr -> (in_channel * out_channel) t
-  val upgrade_ssl : in_channel -> out_channel -> (in_channel * out_channel) t
+  val upgrade_ssl : [ `Not_supported | `Supported of (in_channel -> out_channel -> (in_channel * out_channel) t) ]
   val output_char : out_channel -> char -> unit t
   val output_binary_int : out_channel -> int -> unit t
   val output_string : out_channel -> string -> unit t
diff --git a/pgx/src/pgx.ml b/pgx/src/pgx.ml
index 8465d74..fa97b6f 100644
--- a/pgx/src/pgx.ml
+++ b/pgx/src/pgx.ml
@@ -540,19 +540,26 @@ module Make (Thread : Io) = struct
        StartupMessage. In this case the StartupMessage and all subsequent data will be SSL-encrypted. To continue
        after N, send the usual StartupMessage and proceed without encryption.
        See https://www.postgresql.org/docs/9.3/protocol-flow.html#AEN100021 *)
-    let msg = Message_out.SSLRequest in
-    send_message conn msg
-    >>= fun () ->
-    flush chan
-    >>= fun () ->
-    input_char ichan
-    >>= (function
-    | 'S' ->
-      upgrade_ssl ichan chan
-      >>= fun (ichan, chan) ->
-      return { conn with ichan ; chan }
-    | 'N' -> return conn
-    | _c -> assert false)
+    match Io.upgrade_ssl with
+    | `Not_supported -> return conn
+    | `Supported upgrade_ssl ->
+      Stdlib.print_string "Attempting STARTLS\n";
+      let msg = Message_out.SSLRequest in
+      send_message conn msg
+      >>= fun () ->
+      flush chan
+      >>= fun () ->
+      input_char ichan
+      >>= (function
+      | 'S' ->
+        Stdlib.print_string "Upgrading to TLS\n";
+        upgrade_ssl ichan chan
+        >>= fun (ichan, chan) ->
+        return { conn with ichan ; chan }
+      | 'N' ->
+        Stdlib.print_string "Not upgrading\n";
+        return conn
+      | _c -> assert false)
 
   let connect
       ?host
@@ -603,6 +610,7 @@ module Make (Thread : Io) = struct
         (try Inet (Sys.getenv "PGHOST", port) with
         | Not_found ->
           (* use Unix domain socket. *)
+          Stdlib.print_string "Using Unix socket\n";
           let path = sprintf "%s/.s.PGSQL.%d" unix_domain_socket_dir port in
           Unix path)
     in
diff --git a/pgx_async/src/pgx_async.ml b/pgx_async/src/pgx_async.ml
index 5b37381..bdfd6be 100644
--- a/pgx_async/src/pgx_async.ml
+++ b/pgx_async/src/pgx_async.ml
@@ -82,9 +82,15 @@ module Thread = struct
       >>| fun (_socket, in_channel, out_channel) -> in_channel, out_channel
   ;;
 
-  let upgrade_ssl in_channel out_channel =
-    let config = Conduit_async.V1.Conduit_async_ssl.Ssl_config.configure () in
-    Conduit_async.V1.Conduit_async_ssl.ssl_connect config in_channel out_channel
+  let upgrade_ssl =
+    try
+      let config = Conduit_async.V1.Conduit_async_ssl.Ssl_config.configure () in
+      Stdlib.print_string "TLS supported\n";
+      `Supported (fun in_channel out_channel ->
+        Conduit_async.V1.Conduit_async_ssl.ssl_connect config in_channel out_channel)
+    with _ ->
+      Stdlib.print_string "TLS not supported\n";
+      `Not_supported
 
   (* The unix getlogin syscall can fail *)
   let getlogin () = Unix.getuid () |> Unix.Passwd.getbyuid_exn >>| fun { name; _ } -> name