diff --git a/lib/modules/partition/confirm.fish b/lib/modules/partition/confirm.fish
index 1356b1c3..077cbb84 100644
--- a/lib/modules/partition/confirm.fish
+++ b/lib/modules/partition/confirm.fish
@@ -1,6 +1,6 @@
 #!/bin/env fish
 function confirm -a message default
-    set -l options (echo "[y/n]" | string replace $default (string upper $default))
+    set -l options (echo "[y/n]" | string replace "$default" (string upper "$default"))
 
     while true
         read -l value -P "$message $options "