diff --git a/pythonbuild/buildenv.py b/pythonbuild/buildenv.py
index 696a22df..c93a0f4a 100644
--- a/pythonbuild/buildenv.py
+++ b/pythonbuild/buildenv.py
@@ -44,7 +44,9 @@ def install_toolchain_archive(self, build_dir, package_name, host_platform):
 
         p = build_dir / basename
         self.copy_file(p)
-        self.run(["/bin/tar", "-C", "/tools", "-xf", "/build/%s" % p.name], user="root")
+        self.run(
+            ["/bin/tar", "-C", "/tools", "-xf", "/build/%s" % p.name], user="build"
+        )
 
     def install_artifact_archive(
         self, build_dir, package_name, target_triple, optimizations
@@ -60,7 +62,9 @@ def install_artifact_archive(
         p = build_dir / basename
 
         self.copy_file(p)
-        self.run(["/bin/tar", "-C", "/tools", "-xf", "/build/%s" % p.name], user="root")
+        self.run(
+            ["/bin/tar", "-C", "/tools", "-xf", "/build/%s" % p.name], user="build"
+        )
 
     def install_toolchain(
         self,