diff --git a/nixos/modules/services/misc/gpsd.nix b/nixos/modules/services/misc/gpsd.nix
index a92e06f0902b..99b733d399e2 100644
--- a/nixos/modules/services/misc/gpsd.nix
+++ b/nixos/modules/services/misc/gpsd.nix
@@ -19,6 +19,7 @@ in
     services.gpsd = {
 
       enable = mkOption {
+        type = types.bool;
         default = false;
         description = ''
           Whether to enable `gpsd', a GPS service daemon.
@@ -26,6 +27,7 @@ in
       };
 
       device = mkOption {
+        type = types.str;
         default = "/dev/ttyUSB0";
         description = ''
           A device may be a local serial device for GPS input, or a URL of the form:
@@ -35,6 +37,7 @@ in
       };
 
       readonly = mkOption {
+        type = types.bool;
         default = true;
         description = ''
           Whether to enable the broken-device-safety, otherwise
@@ -51,6 +54,7 @@ in
       };
 
       port = mkOption {
+        type = types.uniq types.int;
         default = 2947;
         description = ''
           The port where to listen for TCP connections.
@@ -58,6 +62,7 @@ in
       };
 
       debugLevel = mkOption {
+        type = types.uniq types.int;
         default = 0;
         description = ''
           The debugging level.