diff --git a/nixos/lib/systemd-unit-options.nix b/nixos/lib/systemd-unit-options.nix
index 8538c8519c53..86bb255a84c3 100644
--- a/nixos/lib/systemd-unit-options.nix
+++ b/nixos/lib/systemd-unit-options.nix
@@ -625,7 +625,7 @@ rec {
 
       listenStreams = mkOption {
         default = [ ];
-        type = types.listOf types.str;
+        type = types.listOf (types.coercedTo types.port toString types.str);
         example = [
           "0.0.0.0:993"
           "/run/my-socket"
diff --git a/nixos/modules/services/network-filesystems/rsyncd.nix b/nixos/modules/services/network-filesystems/rsyncd.nix
index c3d81cb15302..8bae90b6cfda 100644
--- a/nixos/modules/services/network-filesystems/rsyncd.nix
+++ b/nixos/modules/services/network-filesystems/rsyncd.nix
@@ -132,7 +132,7 @@ in
           description = "socket for fast remote file copy program daemon";
           conflicts = [ "rsync.service" ];
 
-          listenStreams = [ (toString cfg.port) ];
+          listenStreams = [ cfg.port ];
           socketConfig.Accept = true;
 
           wantedBy = [ "sockets.target" ];