diff --git a/check_expire b/check_expire
index b2c1c43..f651817 100755
--- a/check_expire
+++ b/check_expire
@@ -99,7 +99,7 @@ try:
             usage()
             sys.exit(STATE_OK)
         elif option == "--hostname" or option == "-H":
-            domain = value
+            domain = value.lower()
         elif option == "--timeout" or option == "-t":
             timeout = int(value) 
         elif option == "--unixtime" or option == "-u":