diff --git a/disko-install b/disko-install
index 9f761b2..330f896 100755
--- a/disko-install
+++ b/disko-install
@@ -78,17 +78,17 @@ parseArgs() {
         exit 1
       fi
       case $2 in
-        format)
-          diskoAttr=diskoScript
-          ;;
-        mount)
-          diskoAttr=mountScript
-          ;;
-        *)
-          echo "Invalid mode: $2" >&2
-          echo "Valid modes are: format, mount" >&2
-          exit 1
-          ;;
+      format)
+        diskoAttr=diskoScript
+        ;;
+      mount)
+        diskoAttr=mountScript
+        ;;
+      *)
+        echo "Invalid mode: $2" >&2
+        echo "Valid modes are: format, mount" >&2
+        exit 1
+        ;;
       esac
       mode=$2
       shift
@@ -163,7 +163,7 @@ main() {
   # shellcheck disable=SC2064
   trap "cleanupMountPoint ${escapeMountPoint}" EXIT
 
-  IFS=$'\n' mapfile -t artifacts < <(nix-build "${libexec_dir}"/install-cli.nix \
+  outputs=$(nix-build "${libexec_dir}"/install-cli.nix \
     "${nix_args[@]}" \
     --no-out-link \
     --impure \
@@ -174,6 +174,8 @@ main() {
     --arg diskMappings "$(serialiaseArrayToNix diskMappings)" \
     -A installToplevel \
     -A "$diskoAttr")
+
+  IFS=$'\n' mapfile -t artifacts <<<"$outputs"
   nixos_system=${artifacts[0]}
   disko_script=${artifacts[1]}
 
diff --git a/install-cli.nix b/install-cli.nix
index 93c0067..1f52419 100644
--- a/install-cli.nix
+++ b/install-cli.nix
@@ -15,7 +15,7 @@ let
           dev = if  diskMappings ? ${name} then
             diskMappings.${name}
           else
-            throw "No device passed for disk '${name}'";
+            throw "No device passed for disk '${name}'. Pass `--disk ${name} /dev/name` via commandline";
         in value // {
           device = dev;
           content = value.content // { device = dev; };