diff --git a/nixos/modules/services/databases/mysql.nix b/nixos/modules/services/databases/mysql.nix
index 4c77efa4bff8..1f32f1d0f5dc 100644
--- a/nixos/modules/services/databases/mysql.nix
+++ b/nixos/modules/services/databases/mysql.nix
@@ -11,10 +11,8 @@ let
   mysqldOptions =
     "--user=${cfg.user} --datadir=${cfg.dataDir} --basedir=${cfg.package}";
 
-  settingsFile = pkgs.writeText "my.cnf" (
-    generators.toINI { listsAsDuplicateKeys = true; } cfg.settings +
-    optionalString (cfg.extraOptions != null) "[mysqld]\n${cfg.extraOptions}"
-  );
+  format = pkgs.formats.ini { listsAsDuplicateKeys = true; };
+  configFile = format.generate "my.cnf" cfg.settings;
 
 in
 
@@ -22,6 +20,7 @@ in
   imports = [
     (mkRemovedOptionModule [ "services" "mysql" "pidDir" ] "Don't wait for pidfiles, describe dependencies through systemd.")
     (mkRemovedOptionModule [ "services" "mysql" "rootPassword" ] "Use socket authentication or set the password outside of the nix store.")
+    (mkRemovedOptionModule [ "services" "mysql" "extraOptions" ] "Use services.mysql.settings.mysqld instead.")
   ];
 
   ###### interface
@@ -96,8 +95,10 @@ in
 
       configFile = mkOption {
         type = types.path;
-        default = settingsFile;
-        defaultText = literalExpression "settingsFile";
+        default = configFile;
+        defaultText = ''
+          A configuration file automatically generated by NixOS.
+        '';
         description = ''
           Override the configuration file used by MySQL. By default,
           NixOS generates one automatically from <option>services.mysql.settings</option>.
@@ -115,7 +116,7 @@ in
       };
 
       settings = mkOption {
-        type = with types; attrsOf (attrsOf (oneOf [ bool int str (listOf str) ]));
+        type = format.type;
         default = {};
         description = ''
           MySQL configuration. Refer to
@@ -148,23 +149,6 @@ in
         '';
       };
 
-      extraOptions = mkOption {
-        type = with types; nullOr lines;
-        default = null;
-        example = ''
-          key_buffer_size = 6G
-          table_cache = 1600
-          log-error = /var/log/mysql_err.log
-        '';
-        description = ''
-          Provide extra options to the MySQL configuration file.
-
-          Please note, that these options are added to the
-          <literal>[mysqld]</literal> section so you don't need to explicitly
-          state it again.
-        '';
-      };
-
       initialDatabases = mkOption {
         type = types.listOf (types.submodule {
           options = {
@@ -324,8 +308,6 @@ in
 
   config = mkIf config.services.mysql.enable {
 
-    warnings = optional (cfg.extraOptions != null) "services.mysql.`extraOptions` is deprecated, please use services.mysql.`settings`.";
-
     services.mysql.dataDir =
       mkDefault (if versionAtLeast config.system.stateVersion "17.09" then "/var/lib/mysql"
                  else "/var/mysql");