diff --git a/pkgs/shells/fish/default.nix b/pkgs/shells/fish/default.nix
index 57c52a411d38..a6ce7bf6d23a 100644
--- a/pkgs/shells/fish/default.nix
+++ b/pkgs/shells/fish/default.nix
@@ -81,18 +81,15 @@ let
       # NIX_PROFILES variable (same as config.environment.profiles)
       set -l __nix_profile_paths (string split ' ' $NIX_PROFILES)[-1..1]
 
-      set __extra_completionsdir \
+      set -p __extra_completionsdir \
         $__nix_profile_paths"/etc/fish/completions" \
-        $__nix_profile_paths"/share/fish/vendor_completions.d" \
-        $__extra_completionsdir
-      set __extra_functionsdir \
+        $__nix_profile_paths"/share/fish/vendor_completions.d"
+      set -p __extra_functionsdir \
         $__nix_profile_paths"/etc/fish/functions" \
-        $__nix_profile_paths"/share/fish/vendor_functions.d" \
-        $__extra_functionsdir
-      set __extra_confdir \
+        $__nix_profile_paths"/share/fish/vendor_functions.d"
+      set -p __extra_confdir \
         $__nix_profile_paths"/etc/fish/conf.d" \
-        $__nix_profile_paths"/share/fish/vendor_conf.d" \
-        $__extra_confdir
+        $__nix_profile_paths"/share/fish/vendor_conf.d"
     end
   '';