diff --git a/modules/clan/phonebox/default.nix b/modules/clan/phonebox/default.nix
index dee12ad..960c461 100644
--- a/modules/clan/phonebox/default.nix
+++ b/modules/clan/phonebox/default.nix
@@ -60,22 +60,21 @@
                 default = null;
               }}";
               number = "${
-                (clanLib.getPublicValue {
+                clanLib.getPublicValue {
                   flake = config.clan.core.settings.directory;
                   machine = machineName;
                   generator = "phonebox";
                   file = "server-prefix-number";
                   default = null;
-                })
-                (
-                  clanLib.getPublicValue {
-                    flake = config.clan.core.settings.directory;
-                    machine = machineName;
-                    generator = "phonebox";
-                    file = "ata-local-number";
-                    default = null;
-                  }
-                )
+                }
+              }${
+                clanLib.getPublicValue {
+                  flake = config.clan.core.settings.directory;
+                  machine = machineName;
+                  generator = "phonebox";
+                  file = "ata-local-number";
+                  default = null;
+                }
               }";
             }) machines;
 
@@ -164,9 +163,20 @@
               };
 
               script = ''
-                cat $prompts/server-prefix-number > $out/server-prefix-number
-                cat $prompts/ata-local-number > $out/ata-local-number
-                cat $prompts/owner-name > $out/owner-name
+                prompt_server_prefix=$(cat "$prompts"/server-prefix-number)
+                if [[ -n "''${prompt_server_prefix-}" ]]; then
+                  echo $prompt_server_prefix | tr -d "\n" > "$out"/server-prefix-number
+                fi
+
+                prompt_ata_local=$(cat "$prompts"/ata-local-number)
+                if [[ -n "''${prompt_ata_local-}" ]]; then
+                  echo $prompt_ata_local | tr -d "\n" > "$out"/ata-local-number
+                fi
+
+                prompt_owner_name=$(cat "$prompts"/owner-name)
+                if [[ -n "''${prompt_owner_name-}" ]]; then
+                  echo $prompt_owner_name | tr -d "\n" > "$out"/owner-name
+                fi
               '';
             };