diff --git a/src/backend/libpq/auth.c b/src/backend/libpq/auth.c
index 3560edc33a0..f327f7bb1bf 100644
--- a/src/backend/libpq/auth.c
+++ b/src/backend/libpq/auth.c
@@ -2363,9 +2363,10 @@ InitializeLDAPConnection(Port *port, LDAP **ldap)
 	if (scheme == NULL)
 		scheme = "ldap";
 #ifdef WIN32
-	*ldap = ldap_sslinit(port->hba->ldapserver,
-						 port->hba->ldapport,
-						 strcmp(scheme, "ldaps") == 0);
+	if (strcmp(scheme, "ldaps") == 0)
+		*ldap = ldap_sslinit(port->hba->ldapserver, port->hba->ldapport, 1);
+	else
+		*ldap = ldap_init(port->hba->ldapserver, port->hba->ldapport);
 	if (!*ldap)
 	{
 		ereport(LOG,
@@ -2489,6 +2490,11 @@ InitializeLDAPConnection(Port *port, LDAP **ldap)
 #define LDAP_NO_ATTRS "1.1"
 #endif
 
+/* Not all LDAP implementations define this. */
+#ifndef LDAPS_PORT
+#define LDAPS_PORT 636
+#endif
+
 /*
  * Return a newly allocated C string copied from "pattern" with all
  * occurrences of the placeholder "$username" replaced with "user_name".