diff --git a/nixos/modules/services/network-filesystems/samba.nix b/nixos/modules/services/network-filesystems/samba.nix
index 410a429621b..fd1e83d9f3e 100644
--- a/nixos/modules/services/network-filesystems/samba.nix
+++ b/nixos/modules/services/network-filesystems/samba.nix
@@ -28,6 +28,7 @@ let
     '';
 
   configFile = pkgs.writeText "smb.conf"
+    (if cfg.configText != null then cfg.configText else
     ''
       [ global ]
       log file = ${logDir}/log.%m
@@ -35,7 +36,7 @@ let
       ${optionalString cfg.syncPasswordsByPam "pam password change = true"}
 
       ${cfg.extraConfig}
-    '';
+    '');
 
   # This may include nss_ldap, needed for samba if it has to use ldap.
   nssModulesPath = config.system.nssModules.path;
@@ -133,6 +134,15 @@ in
         ";
       };
 
+      configText = mkOption {
+        type = types.nullOr types.lines;
+        default = null;
+        description = "
+          Verbatim contents of smb.conf. If null (default), use the
+          autogenerated file from NixOS instead.
+        ";
+      };
+
       securityType = mkOption {
         description = "Samba security type";
         default = "user";