diff --git a/flake.lock b/flake.lock
index a1724e1..555d0cd 100644
--- a/flake.lock
+++ b/flake.lock
@@ -20,15 +20,18 @@
     },
     "nixpkgs": {
       "locked": {
-        "narHash": "sha256-PEQptwFCVaJ+jLFJgrZll2shQ9VI/7xVhrCYkJo8iIw=",
-        "rev": "4f77ea639305f1de0a14d9d41eef83313360638c",
-        "revCount": 490691,
-        "type": "tarball",
-        "url": "https://api.flakehub.com/f/pinned/NixOS/nixpkgs/0.2305.490691%2Brev-4f77ea639305f1de0a14d9d41eef83313360638c/018a70b5-07f4-7ca0-99a2-f4a0ec0a6e07/source.tar.gz"
+        "lastModified": 1701253981,
+        "narHash": "sha256-ztaDIyZ7HrTAfEEUt9AtTDNoCYxUdSd6NrRHaYOIxtk=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "e92039b55bcd58469325ded85d4f58dd5a4eaf58",
+        "type": "github"
       },
       "original": {
-        "type": "tarball",
-        "url": "https://flakehub.com/f/NixOS/nixpkgs/0.2305.%2A.tar.gz"
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
       }
     },
     "root": {
@@ -45,11 +48,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1694139063,
-        "narHash": "sha256-M2dhhe6IzHmS0zQkmnzbcG98jEQGZ4UcS3VcT+rG/Do=",
+        "lastModified": 1701397143,
+        "narHash": "sha256-nYUJxZXwCWWVBYZXPgRxGDuQcZRhKTtD/Jp5Jl+9EWU=",
         "owner": "oxalica",
         "repo": "rust-overlay",
-        "rev": "46dbbcaf435b0d22b149684589b9b059f73f4ffc",
+        "rev": "bb71557c93cad40f5921b2342d7fd69f9e6497ab",
         "type": "github"
       },
       "original": {
diff --git a/flake.nix b/flake.nix
index 1ff2368..207214e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -2,7 +2,7 @@
   description = "Nuenv: a Nushell environment for Nix";
 
   inputs = {
-    nixpkgs.url = "https://flakehub.com/f/NixOS/nixpkgs/0.2305.*.tar.gz"; # Provides Nushell v0.81.0
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable"; # Provides Nushell v0.87.1
     rust-overlay = {
       url = "github:oxalica/rust-overlay";
       inputs.nixpkgs.follows = "nixpkgs";
@@ -128,7 +128,7 @@
             def info [msg: string] { print $"(color "blue" "INFO"): ($msg)" }
             def success [msg: string] { print $"(color "green" $msg)" }
 
-            info $"Hello, NixCon (date now | date format "%Y")!"
+            info $"Hello, NixCon (date now | format date "%Y")!"
             info "So lovely to see everyone today"
             info "Conference status:"
             success "SUCCESS"
diff --git a/nuenv/bootstrap.nu b/nuenv/bootstrap.nu
index 7b10f36..54c8ee9 100644
--- a/nuenv/bootstrap.nu
+++ b/nuenv/bootstrap.nu
@@ -21,7 +21,7 @@ for file in $attrs.__nu_env {
 
 # Set the PATH so that Nushell itself is discoverable. The PATH will be
 # overwritten later.
-let-env PATH = ($attrs.__nu_nushell | parse "{root}/nu" | get root.0)
+$env.PATH = ($attrs.__nu_nushell | parse "{root}/nu" | get root.0)
 
 # Run the Nushell builder
 nu --commands (open $attrs.__nu_builder)
diff --git a/nuenv/builder.nu b/nuenv/builder.nu
index fa1e525..f4655d2 100644
--- a/nuenv/builder.nu
+++ b/nuenv/builder.nu
@@ -1,6 +1,6 @@
 ## Utility commands
 
-source env.nu
+export use env.nu *
 
 ## Parse the build environment
 
@@ -85,7 +85,7 @@ let packagesPath = (
   | each { |pkg| $"($pkg)/bin" } # Append /bin to each package path
   | str join (char esep)      # Collect into a single colon-separated string
 )
-let-env PATH = $packagesPath
+$env.PATH = $packagesPath
 
 # Set user-supplied environment variables (à la FOO="bar"). Nix supplies this
 # list by removing reserved attributes (name, system, build, src, system, etc.).
@@ -96,13 +96,13 @@ if $numAttrs != 0 {
 
   for attr in $drv.extraAttrs {
     if $nix.debug { item $"(yellow $attr.key) = \"($attr.value)\"" }
-    let-env $attr.key = $attr.value
+    load-env {$attr.key: $attr.value}
   }
 }
 
 # Copy sources into sandbox
 if $nix.debug { info "Copying sources" }
-for src in $drv.src { cp -r $src $nix.sandbox }
+for src in $drv.src { cp -r -f $src $nix.sandbox }
 
 # Set environment variables for all outputs
 if $nix.debug {
@@ -113,7 +113,7 @@ for output in ($drv.outputs) {
   let name = ($output | get key)
   let value = ($output | get value)
   if $nix.debug { item $"(yellow $name) = \"($value)\"" }
-  let-env $name = $value
+  load-env {$name: $value}
 }
 
 ## The realisation process
@@ -134,14 +134,14 @@ def runPhase [
     # commands are registered. Right now there's a single env file but in
     # principle there could be per-phase scripts.
     do --capture-errors {
-      nu --log-level warn --env-config $nushell.userEnvFile --commands $phase
+      nu --log-level warn --env-config $nushell.userEnvFile --commands $phase | print
 
       let exitCode = $env.LAST_EXIT_CODE
 
       if ($exitCode | into int) != 0 {
         exit $exitCode
       }
-    } | default {} # To prevent `empty list` being displayed (until Nushell fixes this)
+    }
   } else if $nix.debug { info $"Skipping empty (blue $name) phase" }
 }
 
diff --git a/nuenv/env.nu b/nuenv/env.nu
index 5df813c..3aea2b0 100644
--- a/nuenv/env.nu
+++ b/nuenv/env.nu
@@ -1,32 +1,32 @@
 # Logging
 
-def color [color: string, msg: string] { $"(ansi $color)($msg)(ansi reset)" }
+export def color [color: string, msg: string] { $"(ansi $color)($msg)(ansi reset)" }
 
-def blue [msg: string] { color "blue" $msg }
-def green [msg: string] { color "green" $msg }
-def red [msg: string] { color "red" $msg }
-def purple [msg: string] { color "purple" $msg }
-def yellow [msg: string] { color "yellow" $msg }
+export def blue [msg: string] { color "blue" $msg }
+export def green [msg: string] { color "green" $msg }
+export def red [msg: string] { color "red" $msg }
+export def purple [msg: string] { color "purple" $msg }
+export def yellow [msg: string] { color "yellow" $msg }
 
-def banner [text: string] { print $"(red ">>>") (green $text)" }
-def info [msg: string] { print $"(blue ">") ($msg)" }
-def error [msg: string] { print $"(red "ERROR") ($msg)" }
-def item [msg: string] { print $"(purple "+") ($msg)"}
+export def banner [text: string] { print $"(red ">>>") (green $text)" }
+export def info [msg: string] { print $"(blue ">") ($msg)" }
+export def error [msg: string] { print $"(red "ERROR") ($msg)" }
+export def item [msg: string] { print $"(purple "+") ($msg)"}
 
 # Misc helpers
 
 ## Add an "s" to the end of a word if n is greater than 1
-def plural [n: int] { if $n > 1 { "s" } else { "" } }
+export def plural [n: int] { if $n > 1 { "s" } else { "" } }
 
 ## Convert a Nix Boolean into a Nushell Boolean ("1" = true, "0" = false)
-def envToBool [var: string] {
+export def envToBool [var: string] {
   ($var | into int) == 1
 }
 
 ## Get package root
-def getPkgRoot [path: path] { $path | parse "{root}/bin/{__bin}" | get root.0 }
+export def getPkgRoot [path: path] { $path | parse "{root}/bin/{__bin}" | get root.0 }
 
 ## Get package name fro full store path
-def getPkgName [storeRoot: path, path: path] {
+export def getPkgName [storeRoot: path, path: path] {
   $path | parse $"($storeRoot)/{__hash}-{pkg}" | select pkg | get pkg.0
 }
diff --git a/nuenv/user-env.nu b/nuenv/user-env.nu
index d2b3944..63c48a2 100644
--- a/nuenv/user-env.nu
+++ b/nuenv/user-env.nu
@@ -22,13 +22,15 @@ def relativePath [
 # Display the <msg> in a pretty way.
 def log [
   msg: string # The message to log.
-] { $"(ansi green)+(ansi reset) ($msg)" }
+] {
+  print $"(ansi green)+(ansi reset) ($msg)"
+}
 
 # Output the error <msg> in a flashy way.
 def err [
   msg: string # The error string to log
 ] {
-  $"(ansi red)ERROR(ansi reset): ($msg)"
+  print $"(ansi red)ERROR(ansi reset): ($msg)"
 }
 
 # Check that <file> exists and throw an error if it doesn't.
@@ -67,7 +69,7 @@ def substituteInPlace [
   --replace (-r): string, # The string to replace in <file>
   --with (-w): string # The replacement for <replace>
 ] {
-  $files | each { |file| substitute $file $file --replace $replace --with $with }
+  for $file in $files { substitute $file $file --replace $replace --with $with }
 }
 
 # Display Nuenv-specific commands.