diff --git a/nixos/lib/testing/network.nix b/nixos/lib/testing/network.nix
index 2a188e480ecb..ce019bf27b4d 100644
--- a/nixos/lib/testing/network.nix
+++ b/nixos/lib/testing/network.nix
@@ -13,6 +13,7 @@ let
     nameValuePair
     optionalAttrs
     optionalString
+    optionals
     range
     toLower
     types
@@ -95,16 +96,18 @@ let
           name: config:
           let
             hostnames =
-              optionalString (
-                config.networking.domain != null
-              ) "${config.networking.hostName}.${config.networking.domain} "
-              + "${config.networking.hostName}\n";
+              [
+                "${config.networking.hostName}"
+              ]
+              ++ optionals (config.networking.domain != null) [
+                "${config.networking.hostName}.${config.networking.domain}"
+              ];
           in
           optionalAttrs (config.networking.primaryIPAddress != "") {
-            "${config.networking.primaryIPAddress}" = [ hostnames ];
+            "${config.networking.primaryIPAddress}" = hostnames;
           }
           // optionalAttrs (config.networking.primaryIPv6Address != "") {
-            "${config.networking.primaryIPv6Address}" = [ hostnames ];
+            "${config.networking.primaryIPv6Address}" = hostnames;
           }
         ) nodes;