diff --git a/modules/tasks/swap.nix b/modules/tasks/swap.nix
index 333cf674c077..ab81185532ea 100644
--- a/modules/tasks/swap.nix
+++ b/modules/tasks/swap.nix
@@ -94,7 +94,7 @@ in
               device=$(readlink -f "$device")
               # Add new swap devices.
               if echo $unused | grep -q "^$device\$"; then
-                unused="$(echo $unused | grep -v "^$device\$")"
+                unused="$(echo $unused | grep -v "^$device\$" || true)"
               else
                 ${utillinux}/sbin/swapon "$device" || true
               fi