diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,12 @@
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
+## 0.2.0.1 - 2021-06-16
+
+### Fixed
+
+ - Missing file in sdist
+
 ## 0.2.0.0 - 2021-06-16
 
 ### Added
diff --git a/compat-2.3/include/nix-compat.hh b/compat-2.3/include/nix-compat.hh
new file mode 100644
--- /dev/null
+++ b/compat-2.3/include/nix-compat.hh
@@ -0,0 +1,92 @@
+#pragma once
+#include <nix/store-api.hh>
+#include <nix/derivation-output.hh>
+#include <nix/derivations.hh>
+#include <nix/path-compat.hh>
+
+// derivations.cc
+
+inline void validatePath(std::string_view s) {
+    if (s.size() == 0 || s[0] != '/')
+        throw nix::FormatError("bad path '%1%' in derivation", s);
+}
+
+inline compat::nix::DerivationOutput parseDerivationOutput(const nix::Store & store, std::string drvName,
+    std::string pathS, std::string hashAlgo, std::string hash)
+{
+    if (hashAlgo != "") {
+        auto method = nix::FileIngestionMethod::Flat;
+        if (std::string(hashAlgo, 0, 2) == "r:") {
+            method = nix::FileIngestionMethod::Recursive;
+            hashAlgo = hashAlgo.substr(2);
+        }
+        const auto hashType = nix::parseHashType(hashAlgo);
+        if (hash != "") {
+            validatePath(pathS);
+            return compat::nix::DerivationOutput {
+                .output = nix::DerivationOutputCAFixed {
+                    .drvName = drvName,
+                    .hash = nix::FixedOutputHash {
+                        .method = std::move(method),
+                        .hash = nix::Hash(hash, hashType),
+                    },
+                },
+            };
+        } else {
+            throw nix::Error("ca-derivations not supported in Nix 2.3");
+        }
+    } else {
+        if (pathS == "") {
+            return compat::nix::DerivationOutput {
+                .output = nix::DerivationOutputDeferred { }
+            };
+        }
+        validatePath(pathS);
+        return compat::nix::DerivationOutput {
+            .output = nix::DerivationOutputInputAddressed {
+                .path = parseStorePath(store, pathS),
+            }
+        };
+    }
+}
+
+inline compat::nix::DerivationOutput compatDerivationOutput(nix::Store &store, std::string drvName, nix::DerivationOutput &o) {
+  return parseDerivationOutput(store, drvName, o.path, o.hashAlgo, o.hash);
+}
+
+inline void compatComputeFSClosure(nix::Store &store, nix::StorePathSet &pathSet, nix::StorePathSet &closurePaths, bool flipDirection = false, bool includeOutputs = false, bool includeDerivers = false) {
+  nix::PathSet simpleClosurePaths;
+  store.computeFSClosure(compatPathSet(store, pathSet), simpleClosurePaths, flipDirection, includeOutputs, includeDerivers);
+  for (auto sp : simpleClosurePaths) {
+    closurePaths.insert(parseStorePath(store, sp));
+  }
+}
+
+inline nix::StorePathSet parseStorePathSet(const nix::Store &store, const nix::PathSet &pathSet) {
+  nix::StorePathSet r;
+  for (auto sp : pathSet) {
+    // TODO merge?
+    r.insert(parseStorePath(store, sp));
+  }
+  return r;
+}
+#define parseStorePathSet23(store, pathSet) parseStorePathSet(store, pathSet)
+
+inline std::optional<nix::StorePath> parseOptionalStorePath(const nix::Store &store, const nix::Path path) {
+  if (path != "unknown-deriver" && path != "")
+    return parseStorePath(store, path);
+  return {};
+}
+#define parseOptionalStorePath23(store, path) parseOptionalStorePath(store, path)
+
+#define toDerivedPaths24(x) (x)
+
+namespace nix {
+  StorePathWithOutputs parsePathWithOutputs(const Store &store, const std::string & s);
+}
+
+// util.hh
+
+// C++17 std::visit boilerplate
+template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
+template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
diff --git a/hercules-ci-cnix-store.cabal b/hercules-ci-cnix-store.cabal
--- a/hercules-ci-cnix-store.cabal
+++ b/hercules-ci-cnix-store.cabal
@@ -1,7 +1,7 @@
 cabal-version: 2.4
 
 name:           hercules-ci-cnix-store
-version:        0.2.0.0
+version:        0.2.0.1
 synopsis:       Haskell bindings for Nix's libstore
 category:       Nix
 homepage:       https://docs.hercules-ci.com
@@ -14,6 +14,9 @@
 extra-source-files:
     CHANGELOG.md
     test/data/*.drv
+    compat-2.3/include/*.hh
+    compat-2.3/include/nix/*.hh
+    compat-2.4/include/*.hh
 
 source-repository head
   type: git