diff --git a/TQL b/TQL
index 4b33745f5a5c32e5be74a80c9f09cb42d670f3d5..66755370bbf07582703d08e2bcdd0c2566fd8481 100644
--- a/TQL
+++ b/TQL
@@ -99,6 +99,7 @@ arch: hardware architecture (x86/x64)
 uname: output of uname command
 uptime: uptime of hostname
 load: load average
+os: operating system (linux/windows)
 alloc: host is allowed to be selected to a migration
 hvm: hardware virtualisation enabled
 nvm: vm count on an hypervisor
diff --git a/cccli/handler.py b/cccli/handler.py
index 916960fd0ab4d7b47b1750ae0d19c8e9e909324d..216ea745bf9ff4fd1cb0af1b7a793cdf25936b2d 100644
--- a/cccli/handler.py
+++ b/cccli/handler.py
@@ -43,7 +43,7 @@ class CliHandler(RpcHandler):
     def get_tag_os(self, resolve):
         '''Return Operating system tag'''
         if resolve:
-            return { "value": platform.system(), "ttl": -1 }
+            return { "value": platform.system().lower(), "ttl": -1 }
         return { "ttl": -1 }
 
     def get_tag_uname(self, resolve):