diff --git a/nixos/modules/services/backup/mysql-backup.nix b/nixos/modules/services/backup/mysql-backup.nix
index 31d606b141a..506ded5e9e8 100644
--- a/nixos/modules/services/backup/mysql-backup.nix
+++ b/nixos/modules/services/backup/mysql-backup.nix
@@ -48,6 +48,7 @@ in
       };
 
       user = mkOption {
+        type = types.str;
         default = defaultUser;
         description = ''
           User to be used to perform backup.
@@ -56,12 +57,14 @@ in
 
       databases = mkOption {
         default = [];
+        type = types.listOf types.str;
         description = ''
           List of database names to dump.
         '';
       };
 
       location = mkOption {
+        type = types.path;
         default = "/var/backup/mysql";
         description = ''
           Location to put the gzipped MySQL database dumps.
@@ -70,6 +73,7 @@ in
 
       singleTransaction = mkOption {
         default = false;
+        type = types.bool;
         description = ''
           Whether to create database dump in a single transaction
         '';