diff --git a/lib/krb5/set_default_realm.c b/lib/krb5/set_default_realm.c
index f67d9e6fa..0502403f9 100644
--- a/lib/krb5/set_default_realm.c
+++ b/lib/krb5/set_default_realm.c
@@ -8,16 +8,31 @@ krb5_set_default_realm(krb5_context context,
 {
     const char *foo;
     char *tmp;
+    char **realms = NULL;
 
-    if (realm == NULL)
+    if (realm == NULL){
 	foo = krb5_config_get_string (context->cf,
 				      "libdefaults",
 				      "default_realm",
 				      NULL);
-    else
+	if(foo == NULL){
+	    krb5_error_code ret;
+	    ret = krb5_get_host_realm(context, NULL, &realms);
+	    if(ret)
+		return ret;
+	    foo = realms[0];
+	}
+    } else
 	foo = realm;
 
     tmp = strdup (foo);
+    if(realms){
+	char **q;
+	for(q = realms; *q; q++)
+	    free(*q);
+	free(realms);
+    }
+	
     if (tmp == NULL)
 	return ENOMEM;
     context->default_realm = tmp;