diff --git a/guix/build/python-build-system.scm b/guix/build/python-build-system.scm
index 8429979..1b5eaa8 100644
--- a/guix/build/python-build-system.scm
+++ b/guix/build/python-build-system.scm
@@ -96,6 +96,6 @@
 (define* (python-build #:key inputs (phases %standard-phases)
                        #:allow-other-keys #:rest args)
   "Build the given Python package, applying all of PHASES in order."
-  (apply gnu:gnu-build #:inputs inputs #:phases phases args))
+  (apply gnu:gnu-build #:inputs inputs #:phases (pk 'the-python-phases phases) args))
 
 ;;; python-build-system.scm ends here