diff --git a/nixos/modules/services/misc/synergy.nix b/nixos/modules/services/misc/synergy.nix
index 5b7cf3ac46c3..7990a9f6f4ce 100644
--- a/nixos/modules/services/misc/synergy.nix
+++ b/nixos/modules/services/misc/synergy.nix
@@ -23,12 +23,14 @@ in
 
         screenName = mkOption {
           default = "";
+          type = types.str;
           description = ''
             Use the given name instead of the hostname to identify
             ourselves to the server.
           '';
         };
         serverAddress = mkOption {
+          type = types.str;
           description = ''
             The server address is of the form: [hostname][:port].  The
             hostname must be the address or hostname of the server.  The
@@ -46,10 +48,12 @@ in
         enable = mkEnableOption "the Synergy server (send keyboard and mouse events)";
 
         configFile = mkOption {
+          type = types.path;
           default = "/etc/synergy-server.conf";
           description = "The Synergy server configuration file.";
         };
         screenName = mkOption {
+          type = types.str;
           default = "";
           description = ''
             Use the given name instead of the hostname to identify
@@ -57,6 +61,7 @@ in
           '';
         };
         address = mkOption {
+          type = types.str;
           default = "";
           description = "Address on which to listen for clients.";
         };