diff --git a/default.nix b/default.nix
index ac38de969..4c17420f3 100644
--- a/default.nix
+++ b/default.nix
@@ -5,10 +5,10 @@
 let
   inherit (poetryLib) isCompatible readTOML;
 
-  pyproject-nix = import ./vendor/pyproject.nix { inherit lib; };
+  pyproject-nix = import ./vendor/pyproject.nix { inherit pkgs lib; };
 
   # Name normalization
-  inherit (pyproject-nix.pypa) normalizePackageName;
+  inherit (pyproject-nix.lib.pypa) normalizePackageName;
   normalizePackageSet = lib.attrsets.mapAttrs' (name: value: lib.attrsets.nameValuePair (normalizePackageName name) value);
 
   # Map SPDX identifiers to license names
@@ -172,7 +172,7 @@ lib.makeScope pkgs.newScope (self: {
         in
         lib.listToAttrs (lib.mapAttrsToList (n: v: { name = normalizePackageName n; value = v; }) lockfiles);
 
-      pep508Env = pyproject-nix.pep508.mkEnviron python;
+      pep508Env = pyproject-nix.lib.pep508.mkEnviron python;
 
       # Filter packages by their PEP508 markers & pyproject interpreter version
       partitions =
@@ -181,9 +181,9 @@ lib.makeScope pkgs.newScope (self: {
             if pkgMeta ? marker then
               (
                 let
-                  marker = pyproject-nix.pep508.parseMarkers pkgMeta.marker;
+                  marker = pyproject-nix.lib.pep508.parseMarkers pkgMeta.marker;
                 in
-                pyproject-nix.pep508.evalMarkers pep508Env marker
+                pyproject-nix.lib.pep508.evalMarkers pep508Env marker
               ) else true && isCompatible (poetryLib.getPythonVersion python) pkgMeta.python-versions;
         in
         lib.partition supportsPythonVersion poetryLock.package;
diff --git a/editable.nix b/editable.nix
index 5897212f9..a60aac020 100644
--- a/editable.nix
+++ b/editable.nix
@@ -6,7 +6,7 @@
 , pyproject-nix
 }:
 let
-  name = pyproject-nix.pypa.normalizePackageName pyProject.tool.poetry.name;
+  name = pyproject-nix.lib.pypa.normalizePackageName pyProject.tool.poetry.name;
 
   # Just enough standard PKG-INFO fields for an editable installation
   pkgInfoFields = {
diff --git a/lib.nix b/lib.nix
index 821e49ae7..2aea27ab9 100644
--- a/lib.nix
+++ b/lib.nix
@@ -79,84 +79,6 @@ let
     else if lib.strings.hasInfix "manylinux_" f then { pkg = [ ml.manylinux2014 ]; str = "pep600"; }
     else { pkg = [ ]; str = null; };
 
-  # Predict URL from the PyPI index.
-  # Args:
-  #   pname: package name
-  #   file: filename including extension
-  #   hash: SRI hash
-  #   kind: Language implementation and version tag
-  predictURLFromPypi = lib.makeOverridable (
-    { pname, file, kind }:
-    "https://files.pythonhosted.org/packages/${kind}/${lib.toLower (builtins.substring 0 1 file)}/${pname}/${file}"
-  );
-
-
-  # Fetch from the PyPI index.
-  # At first we try to fetch the predicated URL but if that fails we
-  # will use the Pypi API to determine the correct URL.
-  # Args:
-  #   pname: package name
-  #   file: filename including extension
-  #   version: the version string of the dependency
-  #   hash: SRI hash
-  #   kind: Language implementation and version tag
-  fetchFromPypi = lib.makeOverridable (
-    { pname, file, version, hash, kind, curlOpts ? "" }:
-    let
-      predictedURL = predictURLFromPypi { inherit pname file kind; };
-    in
-    pkgs.stdenvNoCC.mkDerivation {
-      name = file;
-      nativeBuildInputs = [
-        pkgs.buildPackages.curl
-        pkgs.buildPackages.jq
-      ];
-      isWheel = lib.strings.hasSuffix "whl" file;
-      system = "builtin";
-
-      preferLocalBuild = true;
-      impureEnvVars = lib.fetchers.proxyImpureEnvVars ++ [
-        "NIX_CURL_FLAGS"
-      ];
-
-      inherit pname file version curlOpts predictedURL;
-
-      builder = ./fetch-from-pypi.sh;
-
-      outputHashMode = "flat";
-      outputHashAlgo = "sha256";
-      outputHash = hash;
-
-      passthru = {
-        urls = [ predictedURL ]; # retain compatibility with nixpkgs' fetchurl
-      };
-    }
-  );
-
-  fetchFromLegacy = lib.makeOverridable (
-    { python, pname, url, file, hash }:
-    let
-      pathParts =
-        builtins.filter
-          ({ prefix, path }: "NETRC" == prefix)
-          builtins.nixPath;
-      netrc_file = if (pathParts != [ ]) then (builtins.head pathParts).path else "";
-    in
-    pkgs.runCommand file
-      {
-        nativeBuildInputs = [ python ];
-        impureEnvVars = lib.fetchers.proxyImpureEnvVars;
-        outputHashMode = "flat";
-        outputHashAlgo = "sha256";
-        outputHash = hash;
-        NETRC = netrc_file;
-        passthru.isWheel = lib.strings.hasSuffix "whl" file;
-      } ''
-      python ${./fetch_from_legacy.py} ${url} ${pname} ${file}
-      mv ${file} $out
-    ''
-  );
-
   getBuildSystemPkgs =
     { pythonPackages
     , pyProject
@@ -206,8 +128,6 @@ let
 in
 {
   inherit
-    fetchFromPypi
-    fetchFromLegacy
     getManyLinuxDeps
     isCompatible
     readTOML
diff --git a/mk-poetry-dep.nix b/mk-poetry-dep.nix
index feab59fb8..47aa37e15 100644
--- a/mk-poetry-dep.nix
+++ b/mk-poetry-dep.nix
@@ -29,7 +29,7 @@ pythonPackages.callPackage
     }@args:
     let
       inherit (python) stdenv;
-      inherit (pyproject-nix.pypa) normalizePackageName;
+      inherit (pyproject-nix.lib.pypa) normalizePackageName;
       inherit (poetryLib) isCompatible getManyLinuxDeps fetchFromLegacy fetchFromPypi;
 
       inherit (import ./pep425.nix {
@@ -145,7 +145,7 @@ pythonPackages.callPackage
                       pep508Markers = v.markers or "";
                     in
                     compat constraints && (if pep508Markers == "" then true else
-                    (pyproject-nix.pep508.evalMarkers
+                    (pyproject-nix.lib.pep508.evalMarkers
                       (pep508Env // {
                         extra = {
                           # All extras are always enabled
@@ -153,7 +153,7 @@ pythonPackages.callPackage
                           value = lib.attrNames extras;
                         };
                       })
-                      (pyproject-nix.pep508.parseMarkers pep508Markers)))
+                      (pyproject-nix.lib.pep508.parseMarkers pep508Markers)))
                 )
                 dependencies
             );
@@ -215,15 +215,14 @@ pythonPackages.callPackage
             else if isFile then
               localDepPath
             else if isLegacy then
-              fetchFromLegacy
+              pyproject-nix.fetchers.fetchFromLegacy
                 {
                   pname = name;
-                  inherit python;
                   inherit (fileInfo) file hash;
                   inherit (source) url;
                 }
             else
-              fetchFromPypi {
+              pyproject-nix.fetchers.fetchFromPypi {
                 pname = name;
                 inherit (fileInfo) file hash kind;
                 inherit version;
diff --git a/pep425.nix b/pep425.nix
index f5935e140..27cb07cea 100644
--- a/pep425.nix
+++ b/pep425.nix
@@ -1,7 +1,7 @@
 { lib, stdenv, python, pyproject-nix, isLinux ? stdenv.isLinux }:
 let
   inherit (lib.strings) escapeRegex hasPrefix hasSuffix hasInfix splitString removeSuffix;
-  targetMachine = pyproject-nix.pep599.manyLinuxTargetMachines.${stdenv.targetPlatform.parsed.cpu.name};
+  targetMachine = pyproject-nix.lib.pep599.manyLinuxTargetMachines.${stdenv.targetPlatform.parsed.cpu.name};
 
   pythonVer =
     let
diff --git a/vendor/pyproject.nix/default.nix b/vendor/pyproject.nix/default.nix
index bcc49993e..99f6f25e4 100644
--- a/vendor/pyproject.nix/default.nix
+++ b/vendor/pyproject.nix/default.nix
@@ -1,22 +1,5 @@
-{ lib }:
-let
-  inherit (builtins) mapAttrs;
-  inherit (lib) fix;
-in
-
-fix (self: mapAttrs (_: path: import path ({ inherit lib; } // self)) {
-  pip = ./pip.nix;
-  pypa = ./pypa.nix;
-  project = ./project.nix;
-  renderers = ./renderers.nix;
-  validators = ./validators.nix;
-  poetry = ./poetry.nix;
-
-  pep427 = ./pep427.nix;
-  pep440 = ./pep440.nix;
-  pep508 = ./pep508.nix;
-  pep518 = ./pep518.nix;
-  pep599 = ./pep599.nix;
-  pep600 = ./pep600.nix;
-  pep621 = ./pep621.nix;
-})
+{ pkgs, lib }:
+{
+  lib = import ./lib { inherit lib; };
+  fetchers = import ./fetchers { inherit pkgs lib; };
+}
diff --git a/vendor/pyproject.nix/fetchers/default.nix b/vendor/pyproject.nix/fetchers/default.nix
new file mode 100644
index 000000000..1665a2e7c
--- /dev/null
+++ b/vendor/pyproject.nix/fetchers/default.nix
@@ -0,0 +1,122 @@
+{ pkgs
+, lib
+,
+}:
+let
+  inherit (builtins) substring filter head nixPath;
+  inherit (lib) toLower;
+
+  # Predict URL from the PyPI index.
+  # Args:
+  #   pname: package name
+  #   file: filename including extension
+  #   hash: SRI hash
+  #   kind: Language implementation and version tag
+  predictURLFromPypi =
+    {
+      # package name
+      pname
+    , # filename including extension
+      file
+    , # Language implementation and version tag
+      kind
+    ,
+    }: "https://files.pythonhosted.org/packages/${kind}/${toLower (substring 0 1 file)}/${pname}/${file}";
+in
+lib.mapAttrs (_: func: lib.makeOverridable func) {
+  /*
+    Fetch from the PyPI index.
+
+    At first we try to fetch the predicated URL but if that fails we
+    will use the Pypi API to determine the correct URL.
+
+    Type: fetchFromPypi :: AttrSet -> derivation
+    */
+  fetchFromPypi =
+    {
+      # package name
+      pname
+    , # filename including extension
+      file
+    , # the version string of the dependency
+      version
+    , # SRI hash
+      hash
+    , # Language implementation and version tag
+      kind
+    , # Options to pass to `curl`
+      curlOpts ? ""
+    ,
+    }:
+    let
+      predictedURL = predictURLFromPypi { inherit pname file kind; };
+    in
+    pkgs.stdenvNoCC.mkDerivation {
+      name = file;
+      nativeBuildInputs = [
+        pkgs.buildPackages.curl
+        pkgs.buildPackages.jq
+      ];
+      isWheel = lib.strings.hasSuffix "whl" file;
+      system = "builtin";
+
+      preferLocalBuild = true;
+      impureEnvVars =
+        lib.fetchers.proxyImpureEnvVars
+        ++ [
+          "NIX_CURL_FLAGS"
+        ];
+
+      inherit pname file version curlOpts predictedURL;
+
+      builder = ./fetch-from-pypi.sh;
+
+      outputHashMode = "flat";
+      outputHashAlgo = "sha256";
+      outputHash = hash;
+
+      passthru = {
+        urls = [ predictedURL ]; # retain compatibility with nixpkgs' fetchurl
+      };
+    };
+
+  /*
+    Fetch from the PyPI legacy API.
+
+    Some repositories (such as Devpi) expose the Pypi legacy API (https://warehouse.pypa.io/api-reference/legacy.html).
+
+    Type: fetchFromLegacy :: AttrSet -> derivation
+    */
+  fetchFromLegacy =
+    {
+      # package name
+      pname
+    , # URL to package index
+      url
+    , # filename including extension
+      file
+    , # SRI hash
+      hash
+    ,
+    }:
+    let
+      pathParts = filter ({ prefix, path }: "NETRC" == prefix) nixPath; # deadnix: skip
+      netrc_file =
+        if (pathParts != [ ])
+        then (head pathParts).path
+        else "";
+    in
+    pkgs.runCommand file
+      {
+        nativeBuildInputs = [ pkgs.buildPackages.python3 ];
+        impureEnvVars = lib.fetchers.proxyImpureEnvVars;
+        outputHashMode = "flat";
+        outputHashAlgo = "sha256";
+        outputHash = hash;
+        NETRC = netrc_file;
+        passthru.isWheel = lib.strings.hasSuffix "whl" file;
+      } ''
+      python ${./fetch-from-legacy.py} ${url} ${pname} ${file}
+      mv ${file} $out
+    '';
+}
diff --git a/fetch_from_legacy.py b/vendor/pyproject.nix/fetchers/fetch-from-legacy.py
similarity index 85%
rename from fetch_from_legacy.py
rename to vendor/pyproject.nix/fetchers/fetch-from-legacy.py
index 44ea092ac..b39ef5df4 100644
--- a/fetch_from_legacy.py
+++ b/vendor/pyproject.nix/fetchers/fetch-from-legacy.py
@@ -4,37 +4,41 @@
 # Note it is not possible to use pip
 # https://discuss.python.org/t/pip-download-just-the-source-packages-no-building-no-metadata-etc/4651/12
 
-import os
-import sys
 import netrc
-from urllib.parse import urlparse, urlunparse
-from html.parser import HTMLParser
-import urllib.request
+import os
 import shutil
 import ssl
+import sys
+import urllib.request
+from html.parser import HTMLParser
 from os.path import normpath
+from typing import Optional
+from urllib.parse import urlparse, urlunparse
 
 
 # Parse the legacy index page to extract the href and package names
 class Pep503(HTMLParser):
-    def __init__(self):
+    def __init__(self) -> None:
         super().__init__()
-        self.sources = {}
-        self.url = None
-        self.name = None
+        self.sources: dict[str, str] = {}
+        self.url: Optional[str] = None
+        self.name: Optional[str] = None
 
-    def handle_data(self, data):
+    def handle_data(self, data: str) -> None:
         if self.url is not None:
             self.name = data
 
-    def handle_starttag(self, tag, attrs):
+    def handle_starttag(self, tag: str, attrs: list[tuple[str, Optional[str]]]) -> None:
         if tag == "a":
             for name, value in attrs:
                 if name == "href":
                     self.url = value
 
-    def handle_endtag(self, tag):
+    def handle_endtag(self, tag: str) -> None:
         if self.url is not None:
+            if not self.name:
+                raise ValueError("Name not set")
+
             self.sources[self.name] = self.url
         self.url = None
 
@@ -45,14 +49,17 @@ def handle_endtag(self, tag):
 package_filename = sys.argv[3]
 
 # Parse username and password for this host from the netrc file if given.
-username, password = None, None
+username: Optional[str] = None
+password: Optional[str] = None
 if os.environ["NETRC"]:
     netrc_obj = netrc.netrc(os.environ["NETRC"])
     host = urlparse(index_url).netloc
     # Strip port number if present
     if ":" in host:
         host = host.split(":")[0]
-    username, _, password = netrc_obj.authenticators(host)
+    authenticators = netrc_obj.authenticators(host)
+    if authenticators:
+        username, _, password = authenticators
 
 print("Reading index %s" % index_url)
 
diff --git a/fetch-from-pypi.sh b/vendor/pyproject.nix/fetchers/fetch-from-pypi.sh
similarity index 78%
rename from fetch-from-pypi.sh
rename to vendor/pyproject.nix/fetchers/fetch-from-pypi.sh
index e56dee684..e4137c6cd 100644
--- a/fetch-from-pypi.sh
+++ b/vendor/pyproject.nix/fetchers/fetch-from-pypi.sh
@@ -1,4 +1,7 @@
-source $stdenv/setup
+#!/usr/bin/env bash
+
+# shellcheck disable=SC1091,SC2154
+source "$stdenv/setup"
 set -euo pipefail
 
 curl="curl            \
@@ -16,9 +19,9 @@ curl="curl            \
 
 echo "Trying to fetch with predicted URL: $predictedURL"
 
-$curl $predictedURL --output $out && exit 0
+$curl "$predictedURL" --output "$out" && exit 0
 
 echo "Predicted URL '$predictedURL' failed, querying pypi.org"
 $curl "https://pypi.org/pypi/$pname/json" | jq -r ".releases.\"$version\"[] | select(.filename == \"$file\") | .url" > url
 url=$(cat url)
-$curl -k $url --output $out
+$curl "$url" --output "$out"
diff --git a/vendor/pyproject.nix/lib/default.nix b/vendor/pyproject.nix/lib/default.nix
new file mode 100644
index 000000000..bcc49993e
--- /dev/null
+++ b/vendor/pyproject.nix/lib/default.nix
@@ -0,0 +1,22 @@
+{ lib }:
+let
+  inherit (builtins) mapAttrs;
+  inherit (lib) fix;
+in
+
+fix (self: mapAttrs (_: path: import path ({ inherit lib; } // self)) {
+  pip = ./pip.nix;
+  pypa = ./pypa.nix;
+  project = ./project.nix;
+  renderers = ./renderers.nix;
+  validators = ./validators.nix;
+  poetry = ./poetry.nix;
+
+  pep427 = ./pep427.nix;
+  pep440 = ./pep440.nix;
+  pep508 = ./pep508.nix;
+  pep518 = ./pep518.nix;
+  pep599 = ./pep599.nix;
+  pep600 = ./pep600.nix;
+  pep621 = ./pep621.nix;
+})
diff --git a/vendor/pyproject.nix/pep427.nix b/vendor/pyproject.nix/lib/pep427.nix
similarity index 100%
rename from vendor/pyproject.nix/pep427.nix
rename to vendor/pyproject.nix/lib/pep427.nix
diff --git a/vendor/pyproject.nix/pep440.nix b/vendor/pyproject.nix/lib/pep440.nix
similarity index 99%
rename from vendor/pyproject.nix/pep440.nix
rename to vendor/pyproject.nix/lib/pep440.nix
index 0b5f83428..3057ce43d 100644
--- a/vendor/pyproject.nix/pep440.nix
+++ b/vendor/pyproject.nix/lib/pep440.nix
@@ -151,7 +151,7 @@ fix (self: {
   */
   parseVersionCond = cond: (
     let
-      m = match " *([=><!~^]+) *(.+)" cond;
+      m = match " *([=><!~^]*) *(.+)" cond;
       mAt = elemAt m;
     in
     {
@@ -256,6 +256,7 @@ fix (self: {
     "<" = a: b: self.compareVersions a b < 0;
     ">" = a: b: self.compareVersions a b > 0;
     "===" = throw "Arbitrary equality clause not supported";
+    "" = _a: _b: true;
   };
 
 })
diff --git a/vendor/pyproject.nix/pep508.nix b/vendor/pyproject.nix/lib/pep508.nix
similarity index 98%
rename from vendor/pyproject.nix/pep508.nix
rename to vendor/pyproject.nix/lib/pep508.nix
index 04b044771..40f75a18b 100644
--- a/vendor/pyproject.nix/pep508.nix
+++ b/vendor/pyproject.nix/lib/pep508.nix
@@ -3,7 +3,7 @@
 let
   inherit (builtins) match elemAt split foldl' substring stringLength typeOf fromJSON isString head mapAttrs elem length;
   inherit (lib) stringToCharacters fix;
-  inherit (import ./util.nix { inherit lib; }) splitComma;
+  inherit (import ./util.nix { inherit lib; }) splitComma stripStr;
 
   re = {
     operators = "([=><!~^]+)";
@@ -34,9 +34,6 @@ let
     }
   );
 
-  # Strip leading/trailing whitespace from string
-  stripStr = s: let t = match "[\t ]*(.*[^\t ])[\t ]*" s; in if t == null then "" else head t;
-
   # Remove groupings ( ) from expression
   unparen = expr':
     let
diff --git a/vendor/pyproject.nix/pep518.nix b/vendor/pyproject.nix/lib/pep518.nix
similarity index 100%
rename from vendor/pyproject.nix/pep518.nix
rename to vendor/pyproject.nix/lib/pep518.nix
diff --git a/vendor/pyproject.nix/pep599.nix b/vendor/pyproject.nix/lib/pep599.nix
similarity index 100%
rename from vendor/pyproject.nix/pep599.nix
rename to vendor/pyproject.nix/lib/pep599.nix
diff --git a/vendor/pyproject.nix/pep600.nix b/vendor/pyproject.nix/lib/pep600.nix
similarity index 100%
rename from vendor/pyproject.nix/pep600.nix
rename to vendor/pyproject.nix/lib/pep600.nix
diff --git a/vendor/pyproject.nix/pep621.nix b/vendor/pyproject.nix/lib/pep621.nix
similarity index 100%
rename from vendor/pyproject.nix/pep621.nix
rename to vendor/pyproject.nix/lib/pep621.nix
diff --git a/vendor/pyproject.nix/pip.nix b/vendor/pyproject.nix/lib/pip.nix
similarity index 95%
rename from vendor/pyproject.nix/pip.nix
rename to vendor/pyproject.nix/lib/pip.nix
index 8f958cac2..bc78dfc06 100644
--- a/vendor/pyproject.nix/pip.nix
+++ b/vendor/pyproject.nix/lib/pip.nix
@@ -4,14 +4,7 @@
 }:
 let
   inherit (builtins) match head tail typeOf split filter foldl' readFile dirOf hasContext unsafeDiscardStringContext;
-
-  stripStr = s:
-    let
-      t = match "[\t ]*(.*[^\t ])[\t ]*" s;
-    in
-    if t == null
-    then ""
-    else head t;
+  inherit (import ./util.nix { inherit lib; }) stripStr;
 
   uncomment = l: head (match " *([^#]*).*" l);
 
diff --git a/vendor/pyproject.nix/poetry.nix b/vendor/pyproject.nix/lib/poetry.nix
similarity index 89%
rename from vendor/pyproject.nix/poetry.nix
rename to vendor/pyproject.nix/lib/poetry.nix
index 290bf2e85..a389f27d1 100644
--- a/vendor/pyproject.nix/poetry.nix
+++ b/vendor/pyproject.nix/lib/poetry.nix
@@ -4,8 +4,10 @@
 , pep518
 , ...
 }:
+
+lib.fix (self:
 let
-  inherit (builtins) match elemAt foldl' typeOf attrNames head tail mapAttrs;
+  inherit (builtins) match elemAt foldl' typeOf attrNames head tail mapAttrs length filter split;
   inherit (lib) optionalAttrs flatten;
   inherit (import ./util.nix { inherit lib; }) splitComma;
 
@@ -84,55 +86,8 @@ let
     )) [ ]
     (attrNames deps);
 
-  # Supports additional non-standard operators `^` and `~` used by Poetry.
-  # Other operators are passed through to pep440.
-  # Because some expressions desugar to multiple expressions parseVersionCond returns a list.
-  parseVersionCond' = cond: (
-    let
-      m = match "^([~[:digit:]^])(.+)$" cond;
-      mAt = elemAt m;
-      c = mAt 0;
-      rest = mAt 1;
-      # Pad version before parsing as it's _much_ easier to reason about
-      # once they're the same length
-      version = pep440.parseVersion (lib.versions.pad 3 rest);
-    in
-    if m == null then [ (pep440.parseVersionCond cond) ]
-    # Desugar ~ into >= && <
-    else if c == "~" then [
-      {
-        cond = ">=";
-        inherit version;
-      }
-      {
-        cond = "<";
-        version = version // {
-          release = [ (head version.release + 1) ] ++ tail version.release;
-        };
-      }
-    ]
-    # Desugar ^ into >= && <
-    else if c == "^" then [
-      {
-        cond = ">=";
-        inherit version;
-      }
-      {
-        cond = "<";
-        version = version // {
-          release = rewriteCaretRhs version.release;
-        };
-      }
-    ]
-    # Versions without operators are exact matches, add operator according to PEP-440
-    else [{
-      cond = "==";
-      inherit version;
-    }]
-  );
-
   # Normalized version of parseVersionCond'
-  parseVersionConds = s: flatten (map parseVersionCond' (splitComma s));
+  parseVersionConds = s: flatten (map self.parseVersionCond (splitComma s));
 
   dummyMarker = {
     type = "bool";
@@ -240,10 +195,64 @@ in
          build-systems = [ ];  # PEP-518 build-systems (List of parsed PEP-508 strings)
        }
   */
-  # # Analogous to
   parseDependencies = pyproject: {
     dependencies = map parseDependency (normalizeDependendenciesToList (pyproject.tool.poetry.dependencies or { }));
     extras = mapAttrs (_: g: map parseDependency (normalizeDependendenciesToList g.dependencies)) pyproject.tool.poetry.group or { };
     build-systems = pep518.parseBuildSystems pyproject;
   };
-}
+
+  /* Parse a version conditional.
+     Supports additional non-standard operators `^` and `~` used by Poetry.
+
+     Because some expressions desugar to multiple expressions parseVersionCond returns a list.
+
+     Type: parseVersionCond :: string -> [ AttrSet ]
+  */
+  parseVersionCond = cond: (
+    let
+      m = match "^([~[:digit:]^])(.+)$" cond;
+      mAt = elemAt m;
+      c = mAt 0;
+      rest = mAt 1;
+      # Pad version before parsing as it's _much_ easier to reason about
+      # once they're the same length
+      version = pep440.parseVersion (lib.versions.pad 3 rest);
+
+      # Count the number of segments in the input to use an an index in ~ rewriting
+      segments = length (filter (tok: typeOf tok == "string") (split "\\." rest));
+    in
+    if m == null then [ (pep440.parseVersionCond cond) ]
+    # Desugar ~ into >= && <
+    else if c == "~" then [
+      {
+        op = ">=";
+        inherit version;
+      }
+      {
+        op = "<";
+        version = version // {
+          release = lib.imap0 (i: tok: if i >= segments - 1 then 0 else if i == segments - 2 then (tok + 1) else tok) version.release;
+        };
+      }
+    ]
+    # Desugar ^ into >= && <
+    else if c == "^" then [
+      {
+        op = ">=";
+        inherit version;
+      }
+      {
+        op = "<";
+        version = version // {
+          release = rewriteCaretRhs version.release;
+        };
+      }
+    ]
+    # Versions without operators are exact matches, add operator according to PEP-440
+    else [{
+      op = "==";
+      inherit version;
+    }]
+  );
+
+})
diff --git a/vendor/pyproject.nix/project.nix b/vendor/pyproject.nix/lib/project.nix
similarity index 100%
rename from vendor/pyproject.nix/project.nix
rename to vendor/pyproject.nix/lib/project.nix
diff --git a/vendor/pyproject.nix/pypa.nix b/vendor/pyproject.nix/lib/pypa.nix
similarity index 100%
rename from vendor/pyproject.nix/pypa.nix
rename to vendor/pyproject.nix/lib/pypa.nix
diff --git a/vendor/pyproject.nix/renderers.nix b/vendor/pyproject.nix/lib/renderers.nix
similarity index 100%
rename from vendor/pyproject.nix/renderers.nix
rename to vendor/pyproject.nix/lib/renderers.nix
diff --git a/vendor/pyproject.nix/util.nix b/vendor/pyproject.nix/lib/util.nix
similarity index 59%
rename from vendor/pyproject.nix/util.nix
rename to vendor/pyproject.nix/lib/util.nix
index 143d92338..2160d2f0a 100644
--- a/vendor/pyproject.nix/util.nix
+++ b/vendor/pyproject.nix/lib/util.nix
@@ -1,11 +1,19 @@
 # Small utilities for internal reuse, not exposed externally
 { lib }:
 let
-  inherit (builtins) filter match split;
+  inherit (builtins) filter match split head;
   inherit (lib) isString;
 
   isEmptyStr = s: isString s && match " *" s == null;
 in
 {
   splitComma = s: if s == "" then [ ] else filter isEmptyStr (split " *, *" s);
+
+  stripStr = s:
+    let
+      t = match "[\t ]*(.*[^\t ])[\t ]*" s;
+    in
+    if t == null
+    then ""
+    else head t;
 }
diff --git a/vendor/pyproject.nix/validators.nix b/vendor/pyproject.nix/lib/validators.nix
similarity index 100%
rename from vendor/pyproject.nix/validators.nix
rename to vendor/pyproject.nix/lib/validators.nix
diff --git a/vendor/update.py b/vendor/update.py
index 5e3591174..c498351f9 100755
--- a/vendor/update.py
+++ b/vendor/update.py
@@ -1,4 +1,5 @@
-#!/usr/bin/env python3
+#!/usr/bin/env nix-shell
+#! nix-shell -i python3 -p python3
 import subprocess
 import shutil
 import json
@@ -24,8 +25,14 @@
         pass
 
     os.mkdir("pyproject.nix")
+    os.mkdir("pyproject.nix/lib")
 
+    shutil.copy(f"{store_path}/default.nix", f"pyproject.nix/default.nix")
+
+    # Copy lib/
     for filename in os.listdir(f"{store_path}/lib"):
         if filename.startswith("test") or not filename.endswith(".nix"):
             continue
-        shutil.copy(f"{store_path}/lib/{filename}", f"pyproject.nix/{filename}")
+        shutil.copy(f"{store_path}/lib/{filename}", f"pyproject.nix/lib/{filename}")
+
+    shutil.copytree(f"{store_path}/fetchers", "pyproject.nix/fetchers")