Heavily based on a patch from Masahiro Matsuya.

diff -up pam_ldap-185/pam_ldap.c pam_ldap-185/pam_ldap.c
--- pam_ldap-185/pam_ldap.c	2010-09-22 18:35:55.377828002 -0400
+++ pam_ldap-185/pam_ldap.c	2010-09-22 19:08:34.938828001 -0400
@@ -4014,6 +4014,8 @@ pam_sm_acct_mgmt (pam_handle_t * pamh, i
   time_t currenttime;
   long int currentday;
   long int expirein = 0;	/* seconds until password expires */
+  long int expireh = 0;
+  long int expires = 0;
   const char *configFile = NULL;
 
   for (i = 0; i < argc; i++)
@@ -4190,14 +4191,29 @@ pam_sm_acct_mgmt (pam_handle_t * pamh, i
 	}
       else
 	{
-	  expirein = session->info->password_expiration_time / SECSPERDAY;
+          if ( session->info->password_expiration_time != 0 )
+            {
+             expires = session->info->password_expiration_time;
+	      expirein = session->info->password_expiration_time / SECSPERDAY;
+              if ( expirein == 0 )
+                {
+                  expireh = session->info->password_expiration_time / SECSPERHOUR;
+                }
+            }
+          else
+            {
+              expirein = 0;
+            }
 	}
 
-      if (expirein > 0)
+      if ((expirein > 0) || (expireh > 0) || (expires > 0))
 	{
 	  snprintf (buf, sizeof buf,
-		    "Your LDAP password will expire in %ld day%s.",
-		    expirein, (expirein == 1) ? "" : "s");
+		    "Your LDAP password will expire in %ld %s.",
+		    (expirein == 0) ? expireh : expirein,
+		    (expirein == 0) ?
+		    ((expireh == 1) ? "hour" : "hours") :
+		    ((expirein == 1) ? "day" : "days"));
 	  _conv_sendmsg (appconv, buf, PAM_ERROR_MSG, no_warn);
 
 	  /* we set this to make sure that user can't abort a password change */
diff -up pam_ldap-185/pam_ldap.h pam_ldap-185/pam_ldap.h
--- pam_ldap-185/pam_ldap.h	2010-09-22 18:35:55.359828002 -0400
+++ pam_ldap-185/pam_ldap.h	2010-09-22 19:00:56.787828000 -0400
@@ -226,6 +226,9 @@ pam_ldap_shadow_t;
 /* Seconds in a day */
 #define SECSPERDAY 86400
 
+/* Seconds in an hour */
+#define SECSPERHOUR 3600
+
 /* Netscape per-use password attributes. Unused except for DN. */
 typedef struct pam_ldap_user_info
   {