diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8931e50..e3b8e26 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+- `build` shell command for python.
+
 ### Fixed
 - Terraform deploy will now exit with non-zero exit code if deploy failed.
 - Give pylint a $HOME so it won't complain when writing cache and stats.
diff --git a/python/package.nix b/python/package.nix
index 9b7a38c..931f602 100644
--- a/python/package.nix
+++ b/python/package.nix
@@ -121,8 +121,11 @@ let
         description = "Format the code.";
       };
       build = {
-        script = ''eval $buildPhase'';
-        show = false;
+        description = "Build the code";
+        script = ''
+          set +u
+          phases="configurePhase ''${preBuildPhases:-} buildPhase" genericBuild
+        '';
       };
       show-generated-config = {
         script = "$1 --print-generated-config";