diff --git a/nixos/modules/services/web-apps/mattermost.nix b/nixos/modules/services/web-apps/mattermost.nix
index 83c9181ff302..f3d3be43eabc 100644
--- a/nixos/modules/services/web-apps/mattermost.nix
+++ b/nixos/modules/services/web-apps/mattermost.nix
@@ -668,7 +668,7 @@ in
               }
             else if cfg.database.driver == "mysql" then
               {
-                charset = "utf8mb4,utf8";
+                charset = "utf8mb4";
                 writeTimeout = "60s";
                 readTimeout = "60s";
               }
@@ -682,7 +682,7 @@ in
               }
             else if config.mattermost.database.driver == "mysql" then
               {
-                charset = "utf8mb4,utf8";
+                charset = "utf8mb4";
                 writeTimeout = "60s";
                 readTimeout = "60s";
               }