diff --git a/ct/mattermost.sh b/ct/mattermost.sh
index a7015311..8d31bb69 100644
--- a/ct/mattermost.sh
+++ b/ct/mattermost.sh
@@ -11,7 +11,7 @@ var_tags="sync"
 var_cpu="1"
 var_ram="2048"
 var_disk="8"
-var_os="Ubuntu"
+var_os="ubuntu"
 var_version="24.04"
 var_unprivileged="1"
 
diff --git a/json/mattermost.json b/json/mattermost.json
index ccc8c5de..aa2cba33 100644
--- a/json/mattermost.json
+++ b/json/mattermost.json
@@ -21,7 +21,7 @@
                 "cpu": 1,
                 "ram": 2048,
                 "hdd": 8,
-                "os": "Ubuntu",
+                "os": "ubuntu",
                 "version": "24.04"
             }
         }